The edge of the fleshy mantle bears numerous conspicuous, red and orange filamentous tentacles. The shell is thin, solid, equivalve and oval in outline, tapering towards the beaks, and usually about 2.5 cm in length but occasionally reaching 4 cm. The beaks bear an 'ear' like projection on each side, the anterior 'ear' being more prominent. The shell gaps on both sides. The shell is white in young specimens becoming whitish-brown with age. The shell bears clear growth steps and ca 50 radiating ribs that extend to a crenulate margin. When disturbed this species can swim actively using jets of water expelled by 'clapping' its shells together and a rowing motion of its tentacles.