Hmm I've never had spiky moss, but with Java moss you can totally just cut however much you want of it off. I cut it into pieces and then used a sewing thread to tie it against my hardscape--within 4 weeks it had completely attached to the rock and I was able to remove the thread altogether! Some people take their hardscape out and superglue pieces of the moss to hardscape, let the glue dry, and put it back in, but I've always been too scared to use glue in aquariums :\