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:

Primarily an algae grazer.
Scrapes microalgae and films off rocks with its strong teeth (Aristotle’s lantern).
In aquariums, will consume nori, spirulina, and microalgae growth.

Tank Mates:

Peaceful, not aggressive toward fish or invertebrates.
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:

Temperature: 74–80°F (23–27°C)
pH: 8.1–8.4
Salinity: 1.023–1.025
Tank Size: 75+ gallons (needs lots of rock and grazing space)

Unique Features:

Flattened plate-like “spines” form a shell-like armor.
Often looks like a living rock or seashell when seen from above.
One of the few urchins specialized for extreme wave zones.
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.