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:

https://www.huffpost.com/entry/why-do-i-see-patterns-when-i-...

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.