The Red Slate Pencil Urchin, also known as Slate Pencil Urchin, has a reddish-tan body with sparse, long, blunt solid spines that taper at the tips and radiate out from the body in all directions at lengths of up to five inches. In addition to its spines looking like pencils, this sea urchin is also called the Red Slate Pencil Urchin because its spines were used as writing utensils for slate boards.

It can move about via its suctorial podia. It has enough traction to allow it to climb up the glass sides of an aquarium.

Because of its large size, the Red Slate Pencil Urchin will require the solid construction of rocky reefs in the aquarium; rock pieces should be well placed to avoid accidental tumbling and moving around. It can be destructive and harmful to corals, but is safe in a fish-only aquarium. Red Slate Pencil Urchins are generally solitary, and it is generally best to keep just one of its kind per tank. Being nocturnal, it will usually hide during the day and wait for the cover of night to forage for algae. Live rock will provide a good source for grazing. The Red Slate Pencil Urchin prefers low nitrate levels and will not tolerate copper-based medications. It is not unusual for it to lose a few spines, but if it sheds quite a few of them, it is often due to poor water quality.

If there is insufficient algae to graze, the diet should be supplemented with dried seaweed.