Here is Helen’s recipe for an alien:

Grind up some special soap, and add some ground up chalk. Mix with a little water to form a squidgy mess. Leave in a pot for a few days…

This is what happens – hairy squidge:

and a closer look…

Naomi thought it was mould, but the strands are shiny so I think it is crystals growing. Brecon High School science teachers please enlighten us!