Mactra contraria (Contrary Mactra)
Mactridae, also known as surf or trough shells or duck clams, is a family of marine bivalve clams of the order Veneroida.
Moderately thick, triangular in outline,

Photo: Robert Whyte
Mactra contraria (Contrary Mactra)
Trough clams resemble eugaries, but more triangular. white to straw-coloured, to 65mm.

Photo: Robert Whyte
Mactra eximia (A Trough Clam)
Animals live in shallow, subtidal sand, shells often beach-washed.

Photo: Robert Whyte
Mactra eximia (A Trough Clam)
Widespread species, Queensland to north-western Australia.

Photo: Robert Whyte