Here is a list of tutorials I had used to reference to develop my coral forms.

http://www.grasshopper3d.com/video/video/listForContributor?screenName=2buhcnca8l6oy
http://www.youtube.com/watch?v=KZaw6z-w8RA
http://www.youtube.com/watch?v=Y2WJkN1ew4Q&feature=related