This amazing putty will really get you thinking. It looks like it should be a sticky goo, but poke it and it's quite firm.
Mould it in your hands and as it warms up you can watch it change colour. It'll snap if you break it suddenly or tear if you pull it more gently.
Form it into a ball and you can bounce it, pile it up in a mound and watch it slowly melt down flat. The colour will change as the putty warms in your hands.
Colour change putty comes in a cheery yellow tin with that most notorious Springfield resident, Homer, on the lid.
The bottom of the tin says seek medical advice if ingested. To save everyone a whole lot of time we suggest you don't eat it in the first place.