Timo, crinoids, I always called ,em alot of other things :>{ I always liked some of the color that comes from burlington but found it to be tough to work around crystal pockets an real glassy area that run into real course tuff areas. I have a real pretty preform that I,m waiting to get better before I try an finish it, Probably the prettist pc I ever worked on. I,ll try an post pic of said pc. Rick, this piece of material was as wide as it was thick so I had some fun trying to get thin before losing to much width, made sure my platforms were strong an well below center. Worked out good for the amount of experience I have at this time, like I said 6 mo. ago this would have been gravel for sure. Thanks for every ones tips on knapping. Later Bob