I'm wondering because I recently bought another feather duster and stuck it right next to the one I already had. They seemed to move toward one antoher and interlock a few "feathers" for a couple days. Now, niether one has been out for about four days. I looked in the back of the LR where their ends are and I noticed that their tubes are attached now. I was wondering if they were mating or what?
You might try heading over to http://www.reefs.org/library/aquarium_net/ and clicking on Invertebrates and checking out those articles. I have a feeling it's in there somewhere...