- A large wedge-shaped bivalve mollusc of warm seas which burrows into the seabed where it attaches itself by strong byssus threads.
More example sentences
- Family Pinnidae: Pinna and other genera
- Included are pen shells, pearl oysters and a young Tridacna.
- Modern pinnoideans, or ‘pen shells,’ are shallowly to deeply endobyssate, equivalved, edentulous, ham-shaped bivalves with a single, slightly submerged, opisthodetic ligament.
- Perfect for photography, the cave walls and rocky floor are filled with marine life, including pen shells and seahorses.
More definitions of pen shellDefinition of pen shell in:
- The US English dictionary