Tree like growth from pukani live rock

[Royal_pudding]

I Just bought 1 kilo of pukani live rock thats been cycling in a mostly dim container anywhere from 6 months to a couple of years.
I noticed some growth ive never seen before. Anyone know what it could be?
Looks like tree roots tbh. It is solid but bends.

 

[Jay Hemdal Verified Community Expert]

Is it actively growing? It looks a lot like the horny inner skeleton of a Gorgonia.