Congrats! Sure, feather dusters are really worms, they live in a tube made from secretions that bond to salt and other small pieces of hard rocks, etc. to form the tube, where they can quickly escape back to if needed. They are filter feeders and prefer phytoplankton, but I feed my tank and feathers, with zooplankton also. Really helps them get healthy and repopulate. I feed them about 3-4 times per week, just broadcast. You'll never really get to target feed, since they just go back into their tubes. Broadcast feeding is good enough for them, as is stirring your sandbed up to release food that gets into the water column. They are pretty easy creatures, as long as your water gives them something to filter. Helping them grow is all dependent on how much they eat, as as they are filter feeders, the smaller the particles the better.
In the stage yours is in, there isn't much to do except feed as normal. When you target (or broadcast) feed your Blasto, the little guy will benefit, depending on the type of coral food you use. if you use reefroids or something like that, the powdered food that reconstitutes in water, that'll help the little guy. Just don't keep it too clean in the water column, not nasty but put some stuff in the column that will help the worm eat.
Good luck!!!
