Trigoniidae

Trigoniidae is a family of bivalve molluscs belonging to the order Trigoniida. These ancient clams are characterized by their triangular or wedge-shaped shells, which are typically smooth or possess concentric growth lines. A distinctive feature of Trigoniidae is the presence of two prominent cardinal teeth in each valve, which interlock to provide a strong hinge. Many species also exhibit iridescent interiors, known as nacre.

Fossils of Trigoniidae are abundant and widespread, indicating that this family was a significant component of marine ecosystems during the Mesozoic Era. They are considered living fossils due to their long evolutionary history and the fact that many related Mesozoic families are now extinct. While fossil representatives are diverse, the extant (living) members of Trigoniidae are relatively few in number and are found in specific marine environments.

Today, Trigoniidae are primarily found in the Indo-Pacific region, inhabiting sandy or muddy substrates in shallow to moderately deep waters. The living species are ecologically important in their respective habitats, contributing to benthic communities. Due to their limited distribution and the sensitivity of their environments, some living species are considered vulnerable.