Shell small, almost equivalve, inequilateral. Outline elongate-oval usually tapering posteriorly but often distorted and slightly gaping. Height to length ratio varying resulting in shells higher than long or very elongate. Surface irregular. Sculpture of growth lines. Periostracum heavy. Ligament internal on a chondrophore. Pallial sinus deep. Ventral margin smooth.
white with brown perostracum.
common size :
shell to 10 mm.
Very different from Sphenia binghami Turton, 1822 the only other known species of the genus in the Mediterranean. Its main difference is in that the posterior part is narrowly rostrate.
BIOLOGY / ECOLOGY
The Myidae are generally deep burrowers in soft sediments. Sphenia differs from most Myidae in adopting a nestling habit, attached by a weak byssus in crevices and among algae. Suspension feeder.
lives within madreporic rocks and is subjected to numerous deformations. In tunnel. Shells on beach, under stone.