Pin cushion urchins (Lytechinus variegatus) are herbivores that are more active during the evenings. Urchins can be quite clumsy so it is best to keep them in aquariums where the rockwork and corals are fixed securely. These urchins are brilliant at controlling algae growth and keeping rockwork clean. If no algae is present then offer a dried substitute.  These are large urchins suitable for larger aquariums.  They are a minimum of 5cm wide but in many cases up to around 7/8cm wide.  Patterns and colouration can vary between urchins