Originally Posted by poohbear_nc

It is a substance whose structure is a polymer formed by cross linking of polyvinyl alcohol with a boron compound. It can be made at home from polyvinyl-alcohol-based glues, such as Elmer's Glue. It is a non-Newtonian fluid whose combination of fluid-like and solid-like properties makes it a Maxwell solid.
It is a toy.

What is it?