The thamur (or shamir) is a worm with blood that can be used to split the hardest stone, like marble. Solomon discovered this property when he needed to shape marble for an alter without using iron to cut it, which was against Jewish law.

Thomas of Cantimpré describes how the ostrich uses the blood of this Egyptian worm to free its chick when it is imprisoned in a cage made of glass.

See the encyclopedia article The Ostrich and the Thamur for more on this story.