The Shingle urchin, Colobocentrotus atrata (Echinometridae), has a peculiar limpet-life morphology, unique among the regular echinoids.
The aboral spines of Colobocentrotus atrata (on the opposite side to the mouth) are extremely reduced, forming a smooth pavement or plates, and the adoral part (situated near the mouth) is surrounded by a basal skirt of flattened spines. These two features improve the adhesive capacities of the animal and are adaptations to life in areas of extreme wave exposure throughout the Indo West Pacific where this sea urchin lives.
The characteristic spines of the sea urchin Heterocentrotus mamillatus (Echinoida - Echinometridae) really seem crayons, hence its common name.
Spines of sea urchins are appendages that are associated with defense, locomotion, and food gathering. Spines form an important part of an urchin’s maintenance mechanisms, and it is no surprise to find that they are repaired rapidly once damaged.
This species is found in tropical waters of Eastern Africa, Kenya, Madagascar, Marsa Shagra, Mascarene Basin, Mauritius, Red Sea, Seychelles and the West Indian Ocean.
Other common names: Red slate pencil urchin, Red pencil urchin.