What is this?

[AMH Reef]

Hello,
I was hoping for some help id-ing this guy. Showed up in my tank several months ago and was about the size of a dime. It has recently grown pretty large and has been stinging some corals (almost killed a chalice before I realized what was happening) Under white light it's a deep reddish purple. Thanks in advance for any help!

 

[Rocks reef]

It looks like a Pavona coral

 

[BristleWormHater]

Hairy pavona