Animals of which group are not fresh water?

Sea lilies are the members of which class?

Which phylum does an animal belong to that exhibits bilateral symmetry in the larval stage and pentamerous radial symmetry in the adult stage?

$A$ special feature of Evisceration (Autotomy) is found in

Echinoderms are headless,brainless,and heartless. Yet,they are placed at the top of invertebrates because of the presence of:

Animals of the phylum $Echinodermata$ are: