What are these things?

Question
We have had our saltwater tank for about a year now and it seems to be doing excellent but in the last couple of months we have noticed these little white things, they started in the filter, but now have started living in the live rock. I once thought they may have been shrimp larvae but I really don't see how it is possible since we only have one shrimp. But my next guess may be plankton, they are very small, but getting bigger, and white, seem to only really come out of the rocks to eat. Any idea?

Answer

Raschelle,

It sounds like you may have had a hitchhiker on your ( and in) your live rock.  This is typical when using live rock (cured and uncured).   They sound like a harmless invertebrate but it's hard to tell.  They seem to be some Amphipods.  Perhaps you can shoot me over a picture so I can identify them.  Or bring some to your local pet store where they can be looked at.  The other factor is your shrimp could have been impregnated (prior to you buying it) some time ago and eggs were laid and this is the result.

Sorry I could not be more help. let me know about the pic.
Todd