Assertion: echinoderm's body | /r/HasProperty | held rigid
Facets:
value: to form a test
type: PURPOSE
value: by the fused ossicles
type: OTHER
Source sentences:
text: The Echinoidea or sea urchins typically have a compact, nearly spherical body (Figure D) that is held rigid by the fused ossicles to form a test, on which the ambulacra form a nearly symmetrical 5-petaled star.