ID Needed - Live Rock Crustation

[jumpinjammin]

Hi all. So I been battling a couple issues as of lately with my tank. Now I have noticed some crustation on my live rock. Just trying to figure out if it's good or bad.

Any clues? It appears to be hard, and unable to scrub off. Kinda reminds me of coraline. Thanks!

 

[Nibejeebies]

I see what appears to be a turban snail but I don't see anything else...

 

[MarsRover]

Yeah man, maybe help us out by drawing a red circle on the pic as to what you're talking about?

 

[jumpinjammin]

Updated:

 

[jsker]

This would be guessing, sponge growth. I really still can not see from theses pictures:)

 

[donnievaz]

If you can't scrape it off it's most likely coralline.

 

[jumpinjammin]

Thanks, sorry for pics. But it appears to be the best I can do at the moment. :D