Corals form large colonies in shallow tropical water, and coral reefs are made up of the accumulated exoskeletons of the coral polyp. Given these facts, what forms in shallow tropical water among the following options:
- blobfish
 - sub-units of species
 - accumulated exoskeletons
 - aqueous solution
 - polar bears
 - an area swollen with pus
 - swamp vegetation
 - deep-sea dwellers


 

   accumulated exoskeletons      