I always remember the term 'eidetic' and always think I am misremembering the correct term, but it is "eidetic imagery" I am searching for. To me this refers to the phenomenon of seeing above-threshold-of-perception patterns or motions, such as lava-like swirling. As you say, such things can be interesting for a time.
This following link discusses the phenomenon in terms of phosphenes:
Arguably, there have been spiritual movements fueled by relative ignorace around these things, with gurus allegedly claiming that they enable these unexpected experiences for their disciples.
> with gurus allegedly claiming that they enable these unexpected experiences for their disciples
I can voluntarily cause a burst of those color patterns by, after closing my eyes, relaxing all my facial muscles and letting my eyes go unfocused. Works best when trying to fall asleep, so I can imagine people unintentionally doing the same during, say, meditation and correlating it with their spiritual leader.
I think I get phosphenes and never had the word for it. I can more or less elicit them on demand by closing my eyes, relax and let them cross slightly. A stroby concentric circle set ensues for a few seconds. Always the same pattern. Red.
When I close my eye, I usually see an outline of bright/dark somewhat matching what I last saw, but desaturated and splotchy.
If I keep my eyes close, the patches kinda drift around. It's kinda fun to watch sometimes but I get bored eventually open my eyes.
I've always assumed its my eyes just adjusting to the dark, or maybe its residual light my eyelids can't filter out.