Haliotis tuberculata. Fished in the Atlantic, the ear-shaped ormeau (plural ormeaux) is a kind of sea snail with delicate flesh and a beautiful iridescent shell once used to make mother-of-pearl buttons.
Because it is a delicacy, ormers have been overfished; catching them is now strictly controlled and completely banned between June and August. It is very expensive if you find it.
Other names include oreille de mer, ourmée, ormet, ormier, six trous, oreille de Vénus, oreille de Saint-Pierre or haliotide.
Image by user Wolfgang K