EchinoidNomen nescio

Echinoid (Nomen nescio, "I do not know the name"; common name from Echinoidea) are Styx that resemble Tellusian sea urchins.

Despite being rather timid and preferring to hide away, echinoid are notoriously curious and quick to form bonds, often (unwisely) latching onto objects of interest. Echinoid are only defended by their  spiky exteriors, which will harden and become venomous when endangered. Otherwise, they are oddly soft and prone to sticking to things--especially other echinoid--like burs, regardless of material. 

Artwork by lycoris