What is this on my LR

[Torrie]

There is something white on one of my LR, wondering if it is bad.

 

[Flreefer]

I would think that it's just sponge, but can't be positive. Some look spikey.

 

[Torrie]

It is weird feeling it doesn't move or do anything it grows roots and just look likes a spiders web webbed really tight..

 

[Flreefer]

I had the same thing spring up in my tank about 6 months ago, looked just like spider webs, in a big clump. It slowly degraded and now there is just a little stuck between pieces of the rock.

I've read before that it could be a type of snail building it. I'm not sure what type though. Vermatid snails use a webbing as a way to trap food, but these aren't it. Vermatids put out the strand to catch food and pull it back in to eat whatever's on the strand, I've got lots of these too, and I don't think they could cause the webbing effect.
Could be sponge too and either way, I don't think they can be harmful.

If you don't like the looks of them, you could try to blow them apart with a turkey baster. I hit mine a little while blowing off my rocks, and it removed some.
Wish I had better info for you, but I was never able to get a definitive explanation of what caused them.

 

[Torrie]

I don't mind it at all I think it is really cool looking it it trying to spread to my other LR

 

[Flreefer]

If your other rock is close enough, it would probably spread to those as well.
Best of luck with your tank!