Sorry I was in a rush when I posted those other replies.
Yea I feed a cocktail of stuff to my tanks because I believe corals do better with food I just think they are much more healthy this way. I also keep some corals that are hard to keep with out feeding.
I feed bacteria, phyto, and a bunch of other fine foods.
Some sponges feed on stuff as small as bacteria and some larger stuff. Some seem to need nothing other than nutrients from the water.
Over the years some sponges were accidental hitchhiker's on live rock. We see less of this now with so little live rock coming. People also stopped bringing them in because they didn't live and allot of time did not survive shipping or even collection. Allot of sponges can not be exposed to air and that is hard when you are trying to move a ton of corals, fish etc. They had a bad reputation so fish stores did buy them either.
I buy from KP Aquatics. They have allot of sponges and collect themselves so they have some control.
You can see a orange and a yellow sponge in this photo.:
Red sponge. Do not ever let a sponge get sediment on it like this one has.
This one had a few issued and I had to cut some dead parts off it from shipping.
It survived a long time though and grew unit I lost most of my sponges in a move.
When they grow you know you nailed it.