Palliolum furtivum

(Lovén, 1846)

Description (shell):
Shell is fragile, inequilateral, anterior ears at least three times as long as the posterior. Almost equivalve, a small byssal notch in the right anterior ear. Circular in outline, except for the ears. Surface is smooth with fine radiating and concentric lines, but without coarse sculpture except on the anterior ear of the right valve which has 4-6 coarse ribs. Growth stages are clear. Lower margin of byssal notch with teeth which continue along the suture between the valve and the ear, almost to the beaks. Margin is smooth.

Up to 19 mm in length.

Colour very variable, made up into a great variety of patterns of white, cream, grey, pink, yellow, orange, brown or purple and all shades of each.

Lives attached by a byssus when small, later free and capable of swimming by the opening and rapid closing of the valves. The foot is developed as a finger-like organ, occupied in the spinning of byssal threads, which pass through the ears. The mantle margin is double, the inner finely fringed and the outer edged with long tentacles, and at their base gleam a row of large and brilliant ocelli (eye-spots).

Lives offshore between 7- 157 m, normally on bottoms of muddy or gravelly sand.

Not in the southern North Sea. Distributed along the west coasts to the Shetlands and occur from southern Iceland and northern Norway, Skagerak to the Iberian Peninsula and into the Mediterranean (Distr. P. furtivum).