Purple Pincushion Urchin (Echinometra sp.)
The Purple Pincushion Urchin (Echinometra sp.) is an attractive marine grazer recognised by its rounded body and dense covering of purple to reddish-purple spines. Also sold as a Purple-Spined Urchin or Rock-Boring Urchin, it spends much of its time moving across live rock and aquarium surfaces in search of algae, biofilm and organic material. This useful clean-up crew animal can assist with controlling nuisance algae in a mature marine aquarium, although it may also consume coralline algae and move unsecured coral fragments or decorations while grazing.
Key Features
- Rounded body with dense purple to reddish-purple spines
- Active grazer that feeds on algae, biofilm, and organic material
- May inadvertently move or dislodge loose coral fragments or decorations
- Helps maintain algae balance in mature marine tanks
| Feature | Detail |
|---|---|
| Scientific Name | Echinometra sp. |
| Common Names | Purple Pincushion Urchin, Purple-Spined Urchin, Purple Rock-Boring Urchin |
| Feeding Behavior | Grazes on algae, biofilm, and organic matter |
| Habitat | Live rock and aquarium surfaces in marine environments |
FAQ
Can the Purple Pincushion Urchin harm corals in a marine aquarium?
Yes, it may move unsecured coral fragments or decorations while grazing, so it is important to ensure all corals are securely attached before introducing this species.
Does this urchin eat all types of algae?
It primarily targets nuisance algae and biofilm, but may also consume coralline algae, so its grazing behavior should be monitored in a tank with sensitive coral species.
Is the Purple Pincushion Urchin suitable for beginner marine aquariums?
Please contact customer service

Leonard Brown –
Great for keeping algae under control in a mature tank. The urchin moves around the live rock actively and helps reduce green algae buildup. Just make sure all corals are firmly attached to avoid accidental movement.
Nicola Fraser –
It’s a useful addition to my reef tank. I noticed it grazing on the algae on the rock surfaces. It’s not aggressive, but I did see it nudging a small piece of coral that wasn’t secured. Now I check all decorations more carefully.
Alexandra Underwood –
After adding the purple urchin, the algae levels have dropped significantly. It’s a quiet, effective cleaner that doesn’t stress the tank ecosystem. I appreciate its natural behavior in maintaining balance.