Assertion: gastropod's shell | /r/HasProperty | aragonite
Facets:
value: mainly
type: DEGREE
value: almost always
type: TEMPORAL
Source sentences:
text: Shells are almost always composed of polymorphs of calcium carbonate - either calcite or aragonite.
text: The majority of ammonoid specimens, especially those of the Paleozoic era, are preserved only as internal molds; the outer shell (composed of aragonite) has been lost during the fossilization process.
text: Their squeleton, when there is one, is made of chambered univalve shell, composed mainly of aragonite.