food for sponges and sea sqirts

[Pulp Fishin]

I pulled a piece of rock out to take a close look at the cabbage I have on it and noticed about a dozen sea squirtz on the other side.
As well I have a few diffrent sponges growing which all hitchhiked into my system on some used live rock.

I was wondering if there are any additives I should be looking at to aid their feeding?

 

[aromantis]

You could try plankton, or other food for filter feeders. However, if they were hitchhikers they probably should be fine on their own.