Assertion: sponge's spicule | /r/MadeOf | calcium carbonate
Facets:
Source sentences:
text: Spicules, which are present in most but not all species, may be made of silica or calcium carbonate, and vary in shape from simple rods to three-dimensional "stars" with up to six rays.
text: The calcarious sponges are the only group of sponges to have spicules that are made of calcium carbonate.
text: Sponges within the class Calcarea are characterized by spicules made of calcium carbonate.
text: Spicules can be made of silica or calcium carbonate.
text: Leucosolenia is a member of the class Calcarea, and it has spicules made of calcium carbonate.
text: The structure of the commercial sponges (within the class Demospongiae) is based on a skeleton composed of spongin as opposed to the fragile glass sponges in the class Hyalospongiae that feature silicic acid, and the Calcispongiae, which have spicules made of calcium carbonate.