Trilobite Cave

The Trilobite Cave is an optional dungeon in the MARDEK series. It is first available to visit in MARDEK Chapter 2: A New Hero and requires 4 trilobite keys that are hidden in the chapter in order to get to the end of the cave and reach Cambria, a village of trilobites. The locations of the keys are as follows:
*Trilobite Key I is given to you by Gope in the Gem Mine if you spared his life. If you didn't, you must start a new game in order to access the Arena content in MARDEK Chapter 2: A New Hero.
*Trilobite Key II can be found in the Tainted Grotto. Before the corridor where you fought the World's Saviours, there's a little path with a skeleton at the end. If you check the skeleton, you'll find the key in there (look on your map; you'll see a treasure chest, which is invisible in the field screen).
*Trilobite Key III is in Catacombs - B2.
*Trilobite Key IV is dropped randomly by a zombie in Canonia during Moric's invasion. Which one drops it is randomised (actually, each one has about a 10% chance of dropping it until you acquire it), so just keep defeating them until you get it. If you kill them all but still don't have it, just exit the area and come back; they'll all respawn.
All keys can be purchased in Aeropolis in MARDEK Chapter 3: Keystones.
==Monster formations==
Random (all areas except entrance):
*Leech Bat x4
*Trilobite x2
*Coelacanth x3
*Trilobite x1, Coelacanth x2
*Trilobite x2, Coelacanth x2
==Treasures found==
===B1===
*Blood Fossil x1
*Better Potion x3
*643 Gold
*Empty Bottle x4
*Adept's Robe x1
*Liquid Sound x5
===B2===
* Twin Trilobites x1
* Trilobite Scalemail x1
* Body Crystal x1
* Ether x2
* Brazen Protector x1
* 976 Gold
* Mugwort Juice x3
===B3===
* Gold Ring x1
* Gold
* Turquoise Ring x1