ID Help Please

This critter Hitchhiked on my rock and seems to be thriving. Any idea what it could be good or bad?

Thanks in advance for the help.

Terrie

 

Aiptasia anemone, kill it before it invades your tank. There are some products that work, ie Aiptasia X, Joe's Juice, boiling water in a syringe, peppermint shrimp and butterfly fish will sometimes eat it.

 

That's what i was afraid of. Thank you!