when i was feeding my feather dusters on my new rock a pink thing came out of a tunnel.it had many leg things and hide very quick.i couldn't get a picture,to fast. what do you think it is?
Those things are filter feeders. You don't need, actually you can't, feed them anything but phytoplankton. It's all they will accept. I'm not sure what product you are using, but if it is for inverts and fish it is not for your featherduster.