A small short-spined Galapagos urchin that covers itself in shell and weed, so it reads as a moving pile.
Test diameter is not given in any source consulted. A small greenish urchin with short spines, routinely covered in shell fragments, algae and, at polluted sites, plastic debris. That covering habit is the field mark.
The white sea urchin is far larger with dense uniformly short spines and no debris cover.
Shore to a hundred and thirty-four metres on rock. It runs from Colombia to Peru and Ecuador including the Galapagos and the Clarion Islands, so it is not a Galapagos endemic.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.