UNID holothurian (?)

Raja Empat, Papua, Indonesia

Fuji F2 105 mm, 1/90 @ f/27

The question has been raised .. whether this is really a holothurian, or perhaps some kind of urchin (echinoid). Urchins have five teeth (if that's what these are) around their "mouth" - holothurians don't. The experts are looking into the matter, and I'll update this after I hear the final word.