i want it to be like this 

but when i click the minus front, both objects got cut out like this;



so how? how do you combine it like in the first picture?

here the 2 original objects before i click minus front;




Question: Water : Aquatic :: Sand : xxx?
Answer: Well, fancy words for ‘sandy’ are arenarious and arenaceous, with the second apparently preferred.   Perhaps one of those two will do.

You can also use arenaceo- as a combining form.  Darwin did, when he wrote of arenaceo-calcareous loam.



Edit

Oh wait, there is one for just what you want here.  From the OED:


  arenicolous /-ələs/, a. 
  
  Etymology: f. as prec. + -ous.
  
  Inhabiting sand. 
  
  
  1851-9 Owen in Man. Sc. Enq. 381 ― Arenicolous mollusks.
  


The preceding entry referenced above is:


  arenicolite /ærɪˈnɪkəlaɪt/. 
  
  Etymology: f. mod.L. arēnicol-a sand-worm, lob-worm (f. arēna sand + ‑cola inhabiting) + ‑ite.
  
  A worm-hole made originally in sand, and preserved in a sandstone rock. 
  
  1864 in Webster.


Once you remember that Latin had arena for sand (as do Spanish, Italian, Catalan, Portuguese, and various others), the rest is easy: just look for words that start with arena- or areni-, of which we have a fair number.  As another example, arenosity is sandiness.

I also looked for things related to Latin sabulum for gravel, modern French sable for sand, but it was not productive, as all our English uses of sable are related to the furry critter, to black,  or to heraldry.   We have no sabl- words related to sand.