Please help identify

[Wingchunwizard]

Does anyone have any idea what this coral is which came with some live rock? I thought it was a mushroom but after a few days these tentacles decided to appear...

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[Dkuhlmann]

I always forget to check these ID threads, overlook them all the time.

Looks like a ball tip anemone of some sort. They don't get very big and could reproduce quickly so keep an eye on it.