(Müller O.F., 1776)
Description (shell):
Shell is brittle, equivalve and inequilateral, beaks are in front of the midline. Outline is rounded anteriorly but drawn out posteriorly into a blunt bicarinate rostrum. Lunule is indistinct; escutcheon is well defined by a ridged border of the rostrum, elongate lanceolate with fine longitudinal ridges. Sculpture of 30 or more bold concentric ridges. Hinge line with 15-18 teeth in the anterior group and 18-20 in the posterior. Pallial sinus is shallow. Margin is smooth (N. minuta-drawing).
Size:
Up to 19 mm.
Colour:
Periostracum is generally matt though some specimens may be slightly gossy, greenish or greyish yellow in colour.
Animal:
Animal with two siphons, which thrust out beyond the shell and reach up to the water above the mud and sand in which the animal burrows. The purpose of these siphons is to enable the animal to remain safely buried while it gets a constant fresh current of water over its gills, and to bring microscopic food to its mouth. Through the lower of these tubes the fresh supplies pour in, while the vitiated current carrying off waste passes out through the upper tube. With a view to the better protection of these siphons the shell has been elongated backwards.
Habitat:
Muddy sand and gravel from 9-183 m.
Distribution:
Is has a wide distribution in the northern hemisphere. From the Arctic it ranges south in the north Atlantic to the English Channel and the Bay of Lundy and in the north Pacific to California and Japan (Distr. N. minuta).