See text Psychocidaridae is a family of sea urchins in the order Cidaroida.

The family has been in existence since the Lower Jurassic (Toarcian) and the range includes Europe, Ukraine, North America, North Africa and the West Pacific.

Instead they have a single primary tubercle with a large mamelon, the ball-like surface that articulates with the spine.

[2] According to the World Register of Marine Species (WoRMS), the following genera are included in the family:[1] Of these, Psychocidaris is the only extant genus while the other genera are known from fossils.

[1] P. ohshimai is characterized by having gland-shaped spines on the apical (top) surface with a mat of hairs forming an overgrowth and by the oral spines having longitudinal flanges.