Rutland MA
10/1/05
Coral Tooth according to the Internet - the most logical common name
Bear's Head Tooth according to Gary H. Lincoff
Comb Tooth according to Alan E. Bessette
Hericium coralloides

Here is an example where mycologists disagree.  The scientific name is definitely preferable in this case :o) 

NZ and European web sites appear to include completely different looking mushrooms as being Hericium coralloides, as shown on these pages:
http://www.hiddenforest.co.nz/fungi/family/hericiaceae/heric01.htm
http://www.arkive.org/species/ARK/fungi/Hericium_coralloides/
 

Found it growing on a fallen tree that broke into several pieces.  It was quite rotten but still had the bark on.  Could not tell what kind of tree it was.  The fungus was growing on the side of one log section.  It was about 4" wide.  Further on the same log there was signs of another clump forming.

Here is a close-up of the teeth.