I found this guy moving while feeding.

[BrandoCommando]

I'm assuming this is a starfish?

 

[jabberwock]

micro brittle star, good guy

 

[BrandoCommando]

micro brittle star, good guy

Awesome! Any idea how big it could get?

 

[EeyoreIsMySpiritAnimal]

This is a micro brittle star and will not get much (if any) bigger.

 

[jabberwock]

Awesome! Any idea how big it could get?

Not very, "micro" brittle star. Some brittle stars get pretty big but the usually hide under a rock. You see their tentacles most of the time.