Neotrigonia margaritacea, common name the pearly brooch-shell, is a species of saltwater clam, a marine bivalve mollusc in the family Trigoniidae.

This species is known from sandy substrates in shallow seas in southeastern and southwestern Australia.

This species was the first member of the family to be discovered alive; previous to its discovery, trigoniids were only known from fossils.

[3] This clam is capable of opening its shell quite widely; the valves are kept properly aligned and articulated by a series of massive and smaller teeth on the hinge line.

The foot is basically L-shaped, large and muscular, with an additional heel-like lobe.