There is a BIG flame war going on right now over at nano-reef.com about these! I think the scientific name is Crinoid. At least if you Google that you get more information on them.
I will say though, that from what I have read on them there success rate in the home aquaria is very low. No one really knows what exactly they eat or there requirements as far as light and water quality. Some have suggested that they like dirtier water for the nutirents! Just what I have read!
God grant me the serenity to accept the thing's I can not change, the courage to change the thing's I can and the wisdom to know the difference!
R.I.P Walena K. Cox
7/7/62 - 8/11/2002