I remember reading about metamorphosis in lepidoptera (“butterflies”) and how the imago (“adult”) is able to react to stimuli it learned about when it was still a larvae. that might sound kind of boring in itself until you learn that during the pupal stage the nervous system of lepidoptera exists in a very “fluid” state. that knocked my idea of understanding what memory is almost all the way down to zero again.

https://pubmed.ncbi.nlm.nih.gov/6392469/
https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0001736