Small white things on rocks

[er..md]

I have a couple of rocks that have a large number of small white things which appear to be similar to a half a clam shell (kind of like a white limpet only smooth and oval) they are about 3-4 mm in diameter...sorry I can't post a picture but I'm at work at the moment...anybody have any ideas?, they do not appear to be causing harm and appear to ony like one or two of the rocks
thanks

 

[posiden]

My guess is a barnacle.
Here is a shot for size comapreision.

Here is an attempt to ID it. I don't think I was able to get close enough.

 

[er..md]

They look like the first picture but they aren't barnacles..they are soft and I don't see any holes/protrusions

 

[socalnano24]

Originally Posted by ER..MD
http:///forum/post/3129816
They look like the first picture but they aren't barnacles..they are soft and I don't see any holes/protrusions
Sounds like a sponge, almost looks like white bread mold? I've got a few on my rocks, from what I understand they are harmless