Silly putty

My friend was playing with silly putty stuff in Ag class today. He could form it to take any shape and stay solid, stretch it out, and even roll it up into a ball and bounce it off the floor (and it was a pretty high bounce back). That got us wondering......

What's silly putty made out of that makes it able to shape, but also bounce?

*Thanks

Dear lifeoftheparty20,
Silly Putty was an accidental outcome of this experimentation. Created by James Wright, an engineer at General Electric, the substance seemed to have no practical use. However, a local entrepreneur, one Paul Hodgson, bought the rights to the stuff, named it, and started selling Silly Putty through a toy-store catalog.

Silly Putty is composed of flexible molecules that give the material flow.
In case you feel like whipping up a batch at home (not that we recommend this), the main ingredients are:

65% dimethyl siloxane, hydroxy-terminated polymers with boric acid
17% silica, quartz crystalline
9% thixotrol ST
4% polydimethylsiloxane
1% decamethyl cyclopentasiloxane
1% glycerine
1% titanium dioxide

Sue