Lava Lamps patent-free too?

A sidebar in today’s Chicago Tribune certainly implies that, like Coca-Cola, lava lamps are manufactured without patent protection, but as a trade secret.  Invented in 1963, the lava lamp’s patent would long since have expired (tho lawyers seem to know ways to effectively extend such things).

btw, the manufacturer says it isn’t officially called a “lava lamp,” but rather a “Lava brand motion lamp.”