Also known as Cliff-clinging Urchin, Helmet Urchin, Rock Urchin.
Found singly or in groups on strong wave battered shorelines of coastal reefs. Their unique shape helps decrease the chances of being pulled from rocks by the breaking waves.
They feed on coralline algae, periwinkles and other urchins.
Length - 10cm
Depth - 0-5m
Widespread Indo-West Pacific
These sea urchins are a delicacy in Hawaii where they are cracked open to eat their eggs, like "uni" sushi!
Sea Urchins use tubed feet to get around, often in large impenetrable masses for protection.
Sometimes they hitch a lift on the back of crabs.
They have well developed jaws for grinding their prey.
Their anus is on top in most sea urchins, except the heart urchins where it is at the rear.
Predators of sea urchins are triggerfish and large wrasses, who nibble away at their spines before turning them over to eat the fleshy undersides.
Sea Urchins are highly venomous and can piece through a wet-suit.
Some are sensitive to light and have the ability to shoot venom loaded spines at a short distance.
To be avoided!! Ref: https://en.wikipedia.org/wiki/Colobocentrotus_atratus