Bone : pieces of the skeleton of an animal with a backbone.

In archaeology, a bone tool is a tool created from bone. this site will also include shells used as a tool.

A bone tool can conceivably be created from almost any bone, or shell and used in a variety of methods.

Bone tools have been documented from the advent of Homo sapiens and are also known from Homo neanderthalensis contexts or even earlier. Bone has been used for making tools by virtually all hunter-gatherer societies, even when other materials were readily available. Any part of the skeleton can potentially be utilized; however, antlers and long bones provide some of the best working material. Long bone fragments can be shaped, by scraping against an abrasive stone, into such items as arrow and spear points, needles, awls, and fish hooks.  
Definition from Wikipedia