Noticed this growing on my live rock..

[Mrod91]

Tanks been running for about 4 months now, and I noticed this sticking out of my live rock

any idea why? And should I leave it?

 

[muzikalmatt]

Tanks been running for about 4 months now, and I noticed this sticking out of my live rock

any idea why? And should I leave it?

Looks like either a xenia or a clove polyp. Some people consider them invasive and would advise you to remove them before they spread and takeover the rock work. They're both fairly hearty soft corals and easy to take care of. It's up to you if you want to keep it or not.