Shell inequivalve, solid, ovate to elongate-ovate. Area of attachment rather large. The lv is moderately convex. Sculpture of 6-10 well-defined principal radial ribs with strong, depressed, overlapping, spatulate spines. In adults the umbonal area is usually worn. Wide interspaces, with one secondary rib, which bears sharp or slightly flattened overlapping spines. The cardinal area of the upper valve (rv) is triangular and shallow under hingle plate. Inner margin finely crenulate.
shell purple-brown, orange red or deep brick-red. The ribs and spines are the same color as the shell but rarely yellow or lilac colored. Umbonal area often with irregular brown spots, bloches or undulating marks. Internal shell white.
common size :
In the early stages of growth Spondylus species are extremely difficult to identify and many exhibit a similar ornamentation, shape and color. Differences from the very similar S. spinosus in rib number and shape, spine development and color are given under S. spinosus.
BIOLOGY / ECOLOGY
attached to corals or rocks to 150 m.