I bought my grandfather a lava lamp, because he couldn’t sleep in total darkness due to a battle trench collapse in Burma where he was the only survivor.
It was a blue one, so the wax was sort of a lilac purple colour when it got going. He thought it was some space age miracle and took to it like it was his favourite invention.
It was an incongruous sight for a 90 year old to have sitting on his bedside table. Anyway, there’s a use for them other than stoned students sitting in a trance.