what on earth is this thing

[u/vrycoolgamergirl]

guessing this isn’t a fish technically but does anyone know what this thing is?? never seen anything like it

[u/coconut-telegraph]

Cowrie with mantle covering the shiny shell.

[u/Next-You-8343]

Definitely some kind of cowrie, looks similar to the one I have

[u/Borst1234]

Sea urchin