Common name: Long-spined sea urchin

Diadema is a genus of sea urchins known for their long, thin spines, which can be quite sharp and venomous. They are important herbivores on coral reefs, helping to control algae growth. Diadema species often have a symbiotic relationship with various small fish and shrimps that seek refuge among their spines. In the aquarium, they require ample space and plenty of live rock to graze on microalgae. They are sensitive to water quality and should only be introduced to well-established tanks.

1. 
   Common name: long-spined sea urchin

   Scientific name: Diadema antillarum
2. 
   Common name: Sea urchin

   Scientific name: Diadema savignyi
3. 
   Common name: black longspine urchin

   Scientific name: Diadema setosum