Strongylocentrotus fragilis is a species of sea urchin of the family Strongylocentrotidae.

This is a regular sea urchin, with a spherical test bearing the anus on the top and mouth on the bottom.

It is a deep-sea species, and they can occur in great number where food is abundant.

This is an abyssal species, occurring at many hundred meters deep on the western coasts of the North America.

[1] They are distributed throughout the continental shelf and slope, being most abundant in the 200-300m depth range.