Asterstreidia

Asterstreidia are sessile, cnidarian-like Asterzoa. They use modified bait cells to attach to shells or flora, and they have free-swimming developmental stages.

Gymnopolypia (Class)
Asterstreidia which lack a shell and attach directly to rocks or flora.

Selinopolypia (Class)
Asterstreidia which have shells which they can pull their appendages into for protection.