Calveriosoma hystrix is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. Calveriosoma hystrix was first scientifically described in 1872 by Thomson.Kroh, A. (2010). Calveriosoma hystrix (Thomson, 1872). In: Kroh, A. & Mooi, R. (2010) World Echinoidea Database. at the World Register of Marine Species. C. hystrix has a structure known as a siphon, which is a thin tube that runs parallel to the stomach. While its function is not certain, it likely serves a way of moving water from the esophagus to the beginning of the intestine.
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