Strange Coral Growth

[Ryan8696]

Hi everyone - this strange thing has started growing out of my coral recently, does anything know what it could be?

 

[WheatToast]

Looks like Neomeris sp., a rare, green calcified macroalgae:

Neomeris sp. This is a rare calcified green macroalgae that usually dies out in captivity. However, it has a rare chance to go invasive. Since it is calcified, I would assume few organisms could consume it besides urchins.
https://www.marineplantbook.com/marinebookneomeris.htm
https://www.reef2reef.com/threads/neomeris-annulata-reboot-only-option.279012/

 

[Wasabiroot]

Never seen this. Cool find.

 

[kevgib67]

I had these years ago ( way before Google or reef forums). Although I attempted to get it identified so I could defeat it, I couldn’t. The more I manually removed it the faster it grew until it choked out everything and I tore down my tank. I may have been one of the rare few but I recommend buying an urchin asap.