• Salmacis is commonly known as ‘Sea-urchin’.

• Bottom dwelling and slow-moving gregarious echinoderm.

• Body more or less globular, devoid of arms.

• Mouth at center of Oral pole.

• Buccal podia are present.

• At peristomial area, inter radially there are 5 pairs of highly branched, soft and fleshy dermal branchiae – peristomial gills.

• Seen among spines and tube feet are numerous small, club shaped sphaeridia.

• Aristotle’s lantern is the feeding organ.