Mathmos Lavalamps has been made since the year 1963. They are the "real" lavalamps, not like the cheap crappy ones that cost 20€ at a local supermarket. The lamps are a real 70's athmosphere element. Lavalamps where invented near the "flower"power times and where so famous begause people ejoyed the psychedelic figures the lava makes. Lot's of different colors and types of lamps made by Mathmos are really famous still these days. Even I have one.
A lamp with fluids in it,these fluids react differently to the heat that the lamp creates to the bottom of the bottle. That way we get the impression thet the fluids are floating. It looks really smooth, like lava when it's hot.