This bulk material isn't quite clay and it isn't quite paper mache; I would have to say it's somewhere in between. But for an economical product it's pretty hard to beat. Simply add water and sculpt away. Because it has a little plaster in it, this material will harden in a couple of hours and when it's dry, ooh-la-la! Finish with everything from plaster to epoxy to get the effect you want. It's non-toxic for the kids too!
*the picture is of a 10lb. bag but this SKU is for 25lbs.