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A calcisponge is any of a group of marine sponges containing calcareous spicules - spicules which resemble calcium carbonate.
In calcarea spicules are calcareous, in hexactinellida spicules are silicious and hexa radiated, in demospongiae spicules are absent but spongin fibres are present. that's why demosponges are used as bathroom sponges
Sponges don't have skeletons! They are invertebrates which means the creature doesn't have a backbone, but in this case, it doesn't have a skeleton! (I think this is right, I apologize if it isn't)
Spicules provide structural support.
spongin and spicules are the sponges body support and defence
spicules
A calcareous sponge is any of a variety of sponge of the class Calcarea, with skeletons composed of spicules of calcium carbonate.
calcarea - have calcite spicules, often have calcite exoskeletons glass sponges - silica spicules, no exoskeleton demosponges - silica spicules, may have exoskeleton, made of aragonite if present
Sponges have collar cells, osculum, and spicules.
Sponges have collar cells, osculum, and spicules.
Sponges have collar cells, osculum, and spicules.
Sponges have collar cells, osculum, and spicules.