Featherdusters are really worms that secrete a mucus to make their tube their home~! They do not move around the tank. They usually come attached to coral rubble; make sure the bottom end is closed andthe top end is open and not cracked or ripped.
A healthy featherduster will pull back into its tube Quickly when disturbed by movement, a shadow, (ie. if a fish etc is pokingaround looking for food). Otherwise, make sure their crown is visible most of the time, which means it is out filter-feeding.
When you bring it home, don't expose it to the air AT ALL! an air bubble could get in the tube & kill it; make sure you stabilize it in the sand where there is a good current going by to send food to it. When I had mine I would also target feed phytoplankton and turn off the pump for about an hour so it had more time to suck it up!
Hope this helps*SUNSMILE*
ps I don't think they reproduce in tanks; I've read that in the ocean, sometimes when they break in half, the rear part forms its own head and swims off & reproduces in the water