Exhibit 4.3


 


SPECIMEN WARRANT CERTIFICATE


 


	NUMBER	 	[    ] WARRANTS
	WA-	 	 


 


(THIS WARRANT WILL BE VOID IF NOT EXERCISED PRIOR
TO 5:00 P.M.


NEW YORK CITY TIME, FIVE YEARS FROM THE CLOSING
DATE OF THE COMPANY’S INITIAL


BUSINESS COMBINATION)


 


MONTEREY BIO ACQUISITION CORPORATION


 


CUSIP [●]


 


WARRANT


 


THIS WARRANT CERTIFIES THAT, for value received
                                         ,
or registered assigns, is the registered holder of a Warrant or Warrants (the “Warrant”), expiring on a date which is five
(5) years from the completion of the Company’s initial business combination, to purchase one fully paid and non-assessable
share (the “Warrant Shares”), of common stock, par value $0.0001 per share (the “Common Stock”), of Monterey Bio
Acquisition Corporation, a Delaware corporation (the “Company”), for each Warrant evidenced by this Warrant Certificate. This
Warrant Certificate is subject to and shall be interpreted under the terms and conditions of the Warrant Agreement (as defined below).


 


The Warrant entitles the
holder thereof to purchase from the Company, from time to time, in whole or in part, commencing on the later to occur of (i) the completion
of the Company’s initial business combination or (ii) one year following the closing of the Company’s initial public offering,
such number of Warrant Shares at the price of $11.50 per share (the “Warrant Price”), upon surrender of this Warrant Certificate
and payment of the Warrant Price at the office or agency of Continental Stock Transfer & Trust Company (the “Warrant Agent”),
such payment to be made subject to the conditions set forth herein and in the Warrant Agreement, dated [●], 2021, between the Company
and the Warrant Agent (the “Warrant Agreement”). In no event shall the registered holder(s) of this Warrant be entitled to
receive a net-cash settlement in lieu of physical settlement in Warrant Shares of the Company. The Warrant Agreement provides that, upon
the occurrence of certain events, the Warrant Price and the number of Warrant Shares purchasable hereunder, set forth on the face hereof,
may be adjusted, subject to certain conditions. The term Warrant Price as used in this Warrant Certificate refers to the price per full
Warrant Share at which Warrant Shares may be purchased at the time the Warrant is exercised.


 


This Warrant will expire
on the date first referenced above if it is not exercised prior to such date by the registered holder pursuant to the terms of the Warrant
Agreement or if it is not redeemed by the Company prior to such date.


 


No fractional shares will
be issued upon any exercise of a Warrant. If, upon exercise of a Warrant, a holder would be entitled to receive a fractional interest
in a share, the Company will, upon exercise, issue or cause to be issued only the largest whole number of Warrant Shares issuable on such
exercise (and such fraction of a share will be disregarded).


 


Upon any exercise of the
Warrant for less than the total number of full Warrant Shares provided for herein, there shall be issued to the registered holder(s) hereof
or its assignee(s) a new Warrant Certificate covering the number of Warrant Shares for which the Warrant has not been exercised.


 


Warrant Certificates, when
surrendered at the office or agency of the Warrant Agent by the registered holder(s) hereof in person or by attorney duly authorized in
writing, may be exchanged in the manner and subject to the limitations provided in the Warrant Agreement, but without payment of
any service charge, for another Warrant Certificate or Warrant Certificates of like tenor and evidencing in the aggregate a like number
of Warrants.


 


Upon due presentment for registration of
transfer of the Warrant Certificate at the office or agency of the Warrant Agent, a new Warrant Certificate or Warrant Certificates of
like tenor and evidencing in the aggregate a like number of Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided in the Warrant Agreement, without charge except for any applicable tax or other governmental
charge.


 


The Company and the Warrant
Agent may deem and treat the registered holder(s) as the absolute owner(s) of this Warrant Certificate (notwithstanding any notation of
ownership or other writing hereon made by anyone) for the purpose of any exercise hereof, of any distribution to the registered holder(s),
and for all other purposes, and neither the Company nor the Warrant Agent shall be affected by any notice to the contrary.


 


This Warrant does not entitle the registered holder(s)
to any of the rights of a stockholder of the Company.


 






    


     


    

 


After the Warrant
becomes exercisable and prior to its expiration date, the Company reserves the right to call the Warrant at any time, with a notice
of call in writing to the holder(s) of record of the Warrant, giving thirty (30) days’ written notice of such call if the last
reported sale price of the Common Stock has been equal to or greater than $16.50 per share for any twenty (20) trading days within a
thirty (30) trading day period ending on the third (3rd) trading day prior to the date on which notice of such call is given,
provided that (i) a registration statement under the Securities Act of 1933, as amended (the “Act”) with respect to the
shares of Common Stock issuable upon exercise must be effective and a current prospectus must be available for use by the registered
holders hereof or (ii) the Warrants may be exercised on cashless basis as set forth in the Warrant Agreement and such cashless
exercise is exempt from registration under the Act. The call price is $0.01 per Warrant Share. No fractional shares will be issued
upon exercise of the Warrant.


 


If the foregoing conditions
are satisfied and the Company calls the Warrant for redemption, each holder will then be entitled to exercise his, her or its Warrant
prior to the date scheduled for redemption; provided that the Company may require the Registered Holder who desires to exercise the Warrant,
to elect cashless exercise as set forth in the Warrant Agreement, and such Registered Holder must exercise the Warrants on a cashless
basis if the Company so requires. Any Warrant either not exercised or tendered back to the Company by the end of the date specified in
the notice of call shall be canceled on the books of the Company and have no further value except for the $0.01 call price.


 


	By	 	 
	 	Chief Executive Officer	 


 






    


     


    

 


[REVERSE OF CERTIFICATE]


 


SUBSCRIPTION FORM


 


To Be Executed by the Registered Holder(s) in Order
to Exercise Warrants


 


The undersigned hereby irrevocably
elects to exercise the right, represented by this Warrant Certificate, to receive shares of Common Stock in accordance with the terms
of this Warrant Certificate and pursuant to the method selected below. Capitalized terms used herein and not otherwise defined have the
respective meanings set forth in the Warrant Certificate. PLEASE CHECK ONE METHOD OF PAYMENT:


 


	 	 	 	 	 
	 	 	 	 	a “Cash Exercise” with respect to                  Warrant Shares; and/or
	 	 	 	 
	 	 	 	 	a “Cashless Exercise” with respect to                  Warrant Shares because on the date of this exercise, there is no effective registration statement registering the Warrant Shares, or the prospectus contained therein is not available for the resale of the Warrant Shares, in which event the Company shall deliver to the registered holder(s)                  shares of Common Stock pursuant to Section 3.3.2 of the Warrant Agreement.


 


The undersigned requests that a certificate for
such shares be registered in the name(s) of:


 


	 
	(PLEASE TYPE OR PRINT NAME(S) AND ADDRESS)
	 
	 
	 
	 
	 
	 
	 
	(SOCIAL SECURITY OR TAX IDENTIFICATION NUMBER(S))


 


	and be delivered to	 	 
	 	 	(PLEASE PRINT OR TYPE NAME(S) AND ADDRESS)


 


and, if such number of Warrants shall not be all
the Warrants evidenced by this Warrant Certificate, that a new Warrant Certificate for the balance of such Warrants be registered in the
name of, and delivered to, the registered holder(s) at the address(es) stated below:


 


Dated:


 


	 	 
	(SIGNATURE(S))	 
	 	 
	 	 
	(ADDRESS(ES))	 
	 	 
	 	 
	 	 
	 	 
	(TAX IDENTIFICATION NUMBER(S))	 


 






    


     


    

 


ASSIGNMENT


 


To Be Executed by the Registered Holder in Order
to Assign Warrants


 


For Value Received,                                     
hereby sell(s), assign(s), and transfer(s) unto


 


	 
	(PLEASE TYPE OR PRINT NAME(S) AND ADDRESS(ES))
	 
	 
	 
	 
	 
	 


 


(SOCIAL SECURITY OR TAX IDENTIFICATION NUMBER(S))


 


	and to be delivered to	 	 
	 	 	(PLEASE PRINT OR TYPE NAME(S) AND ADDRESS(ES))
	 
	 
	 
	 


 


(SOCIAL SECURITY OR TAX IDENTIFICATION NUMBER(S))


 


of the Warrants represented by this Warrant Certificate,
and hereby irrevocably constitute and appoint                     
Attorney to transfer this Warrant Certificate on the books of the Company, with full power of substitution in the premises.


 


Dated:


 


	 	 
	(SIGNATURE(S))	 


 


NOTICE: THE SIGNATURE(S) TO THIS ASSIGNMENT MUST
CORRESPOND WITH THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE
WHATEVER.


 


Signature(s) Guaranteed:


 


	By	 	 


 


THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE
GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE
MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15).