Mine is that at my age (barely made it into Gen Z on the old end) I just found out today that a Bo Weevil is an insect (beetle) and not some kind of mole or similar rodent.
I do have an inner monologue and when I try to visualise something the closest thing I can get is my inner monologue describing the features of the thing I’m trying to see. But no picture appears. It’s like my brain only saves the concepts of things, like an apple is round, red, has a little brown stem etc.