Challenge #8 Culture

*Introduced in 1963, it was a huge fad of the 1960s and 1970s when millions were sold; it became popular again in the late 1990s.

*It is a capped glass container holding two compounds that are similar in density and don't mix, with a source of light and heat at the bottom.

*When the unit is turned off and becomes cold, the denser compound sinks to the bottom in a hard, waxy, flat lump.

*With heat, the denser compound liquefies and expands, becoming less dense than the water, and it slowly rises to the surface.

*The risen blobs of compound cool when away from the source of heat, and they fall back to the bottom, to continue the process of rising and falling until the device is turned off.