Shells of the Frond Oyster, Dendostrea frons (Linnaeus, 1758), can be found on island beaches usually attached to other objects. The shell outline is variable (see pictures), and usually conforms to the shape of the objects the oyster is attached to: very elongate when attached to Sea Whips, or rounded when living on rocks or other hard substrates. Claw-like projections "hook" the shells onto stems of Sea Whips. Frond Oysters belong to the same family as the edible oysters, the family Ostreidae.
The Frond Oyster, Dendostrea frons (Linnaeus, 1758). The two images on the left represent a Frond Oyster that grew along a Sea Whip.