Sunflower Sea Star (Pycnopodia helianthoides)

Looks to be some kind of Sea anemone?

I don't think so, because if you flip it over you can see thousands of little arms. The guy who caught this says its a starfish but none of us could identify it.

Pycnopodia helianthoides

Thanks a lot ^_^ The people here really help new comers. By the way, are these things poisonous? This one had little spikes on the sides of each arm.

Well now that I know, from some research:

Natural History: This is our largest and fastest sea star. Its soft, flexible body and numerous tube feet allow it to move quickly. It has been observed moving over sand or gravel at speeds up to 3 meters per minute. It feeds upon a large variety of organisms which include urchins, sand dollars, bivalves and sea cucumbers. It will also scavenge upon dead fish. Its mere presence causes many animals to show a dramatic escape response.

Nothing about it being poisonous though

Okay, thanks again :d

The only Echinoderms (this is an Echinoderm) known (a few species) to be poisonous are in Class Echinoidea (Sea Urchins).

Oh cool, because I freaked out when I saw this dark blue Seastar with maroon spines a few inches away from my leg when we went snorkling and me and my dad decided to go closer to shore.