Please follow the link to my YouTube video of my 100 litre reef tank. I need to identify the purple 'thing'(!) that's growing out of my live rock to the left of the Branching Octopus coral.
I keep cutting it out but it returns. It is slow growing and feels semi-hard to the touch.
All my levels are within spec (I think!). Does this need to be removed completely or is it a benign growth?