The lava lamp celebrates its 50th birthday Tuesday, and though it’s more kitsch than classic design, the piece remains just as memorable as mid-century furnishings from Eames, Noguchi and Saarinen.

The British-made lamps have surged in popularity as younger audiences seek to recapture magic of the 1960s Depending on your age, you may remember them from Doctor Who and The Prisoner in the 1960s, ...