What is this? Algae? Coral?

[redvicki]

Okay this has been on my rock since I bought it. My rock came from an established reef tank. At first it just looked like someone had rubbed mustard on the rock. The rock was stored in a dark trash can for 3 weeks. Since it is now in my tank and I have started running my lights I've noticed something new with my mustard. It seems to have become a little spikey, it's no longer smooth, and it has little things poking out of it. They are round and from my angle appear almost clear. There are 5 or 6 of these and they are not visable all of the time and are very small but noticiable. Any thoughts on what it is and how I should handle it? Feed it or kill it? Thanks

 

[sassafrass]

It looks like a sponge to me ,totally harmless filter feeder.

 

[reefworm]

pic is too fuzzy to make out. in what part of the picture is the item you want us to see?

 

[Sk8r]

Probably sponge. Good hitchhiker. Feed phyto if you want to see it grow.

 

[redvicki]

It's the very yellow thing on the bottom of the rock. Sorry about the bad picture hard to get a good shot of it since it's on the bottom of the rock under a ledge.

 

[reefworm]

OK - I'd guess encrusting sponge as well. just make sure it doesn't overgrow anything.

 

[padi200]

yup, it is a sponge