Assertion: sand dollar | /r/HasAspect | opening
Facets:
value: like urchins
type: OTHER
value: on the ventral surface
type: LOCATION
Source sentences:
text: Like urchins, sand dollars have an opening on the ventral surface called a peristome and a dorsal opening called a periproct, although in sand dollars the periproct is located on the margin of the animal.