Family
Common name: Pencil Urchins
Scientific name: Cidaridae 
Cidaridae, commonly known as Pencil Urchins, are a family of sea urchins characterized by their thick, blunt spines that resemble pencils. They are found in various marine environments from shallow reefs to deep-sea habitats. Pencil Urchins are known for their hardy nature and ability to adapt to different conditions, making them a suitable choice for reef aquariums. They play a beneficial role in the tank by grazing on algae, helping to keep the aquarium clean. However, their spines can be sharp and may harm more delicate tank inhabitants.
- Common name: Pencil UrchinScientific name: Eucidaris metularia
 - Common name: slate pencil urchinScientific name: Eucidaris tribuloides
 - Common name: Slate Pencil UrchinScientific name: Goniocidaris tubaria
 
Common name: Imperial Sea UrchinScientific name: Phyllacanthus imperialis- Common name: Cidaroid Sea UrchinScientific name: Plococidaris verticillata
 - Common name: Crown-spined Pencil UrchinScientific name: Prionocidaris baculosa
 - Common name: Pencil Sea UrchinScientific name: Prionocidaris bispinosa
 - Common name: red lance urchinScientific name: Stylocidaris affinis