Description
Armadillo Sea Urchin – Colobocentrotus sp.
(Also called the Helmet Urchin, Shingle Urchin, or Armored Urchin)
Overview:
Unlike typical spiny urchins, the Armadillo Urchin has a smooth, domed shell covered with flattened, tile-like plates rather than sharp spines. These plates interlock like armor, giving it an armadillo-like appearance and making it incredibly resistant to the crashing surf of wave-swept rocky shores. Its strange armored body allows it to cling tightly to rocks, even in areas of strong currents where other urchins cannot survive.
Origin:
Native to the tropical Indo-Pacific, often found in high-energy, wave-exposed rocky coasts.
Feeding:
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Primarily an algae grazer.
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Scrapes microalgae and films off rocks with its strong teeth (Aristotle’s lantern).
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In aquariums, will consume nori, spirulina, and microalgae growth.
Tank Mates:
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Peaceful, not aggressive toward fish or invertebrates.
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Reef safe in terms of not eating corals, but may disturb rockwork or corals while moving.
Aggression Level:
Peaceful – fully armored but not predatory.
Experience Level:
Intermediate. Easier to keep than venomous species like Asthenosoma varium, but requires strong water flow and plentiful algae.
Water Parameters:
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Temperature: 74–80°F (23–27°C)
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pH: 8.1–8.4
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Salinity: 1.023–1.025
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Tank Size: 75+ gallons (needs lots of rock and grazing space)
Unique Features:
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Flattened plate-like “spines” form a shell-like armor.
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Often looks like a living rock or seashell when seen from above.
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One of the few urchins specialized for extreme wave zones.
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Very rare in the aquarium trade due to its specialized habitat.
✨ The Armadillo Sea Urchin is one of the most unusual echinoderms, valued for its armored, spiny-free look. It’s more of a collector’s specimen than a common reef inhabitant.
