the galileo bone -->
kinda looks like light wood and it's HEA-VY! It looks pretty cool when they're being "chewed." by that, I mean that all it has are scratches on the surface, I think it'd be Highly unlikely for a dog to be able to puncture it, much less to even break a piece off! oh, & be careful when the dog's playing with it, that thing FLIES & lands hard, as u can imagine... check it out @ the store & see what you think.
here's the 2 sizes.. .though I'm sure they have more on the market:
here's another link: http://www.thepuppyshop.com/galileochewtoy.html