This is a photo by Shahaira of a Flamingo Tongue Snail (Cyphoma gibbosum)! I would have guessed it to be someone’s embroidery project! Per Wikipedia, this little critter lives “in the tropical waters of the Western Atlantic Ocean, including the Caribbean Sea, the Gulf of Mexico and the Lesser Antilles. It can also be found from North Carolina, the Bermudas to Northern Brazil.”
The bright colors are only on the soft tissue which surrounds the shell; the shell is normally white or pinkish. Our little snail likes to feed on toxic sea fans and ingest the fans’ venom, becoming toxic itself!