Echinocardium pennatifidum is a species of sea urchin in the family Loveniidae, chiefly found in the northeast Atlantic region.
Echinocardium pennatifidum is up to long. It has coarser, more regularly arranged spines than other Echinocardium. The frontal ambulacrum is flush with the front of the heart-shaped test. It has a short , not reaching the second pair of ambulacral plates. The specific name means "cut into the shape of a feather." This species is critically distinguished from Echinocardium flavescens by its short labrum and the absence of larger spines in the interambulacral areas of the upper side of the test. Up to 7cm in length.
Found in the waters off Great Britain, Ireland, the North Sea and associated islands.
Echinocardium pennatifidum buries itself in coarse sand or fine shell gravel in the sublittoral, from low on shore to depths of .