There's a simple formula behind these eco-friendly toys designed by Noa Himelfarb: Kids like dirt + kids like animals + kids like building = Muzoo. So instead of creating a creature from a potato, they use a lump of mud.

The Muzoo kit consists of a simple frame that makes it easier for artistically challenged kids to sculpt a lump of mud into a lion, giraffe, or elephant. As well as plastic accessories that serve as ears, tails, and manes so they don't have to make quite as big a leap with their imaginations to bring them to life.

In fact the Muzoo probably isn't limited to just use with mud. Plasticine would work just as well. But once kids get tired of the animal they've made, it's far easier and more environmentally friendly for them to just crumble their creation to the ground, and start again. [Noa Himelfarb via Inhabitat]