This (and the human brain in general) is fascinating to me. I've always been on the opposite end of aphantasia, although I've never been officially diagnosed with hyperphantasia. I don't understand it at all it just seems natural.

When there's a question about physical objects I close my eyes and just check. It's not that my memory is particularly good but I can "synthesize" shapes. I might tell myself a story like, "Start with a point. Expand it into a line segment. Now pull that line parallel to itself to create a rectangle. You can spin that plane around a bit and then grab a point in the middle and pull it up into a pyramid. And so on. I basically watch a color-coded animation when I say something like that.

With music it can be a bit distracting. I'll go through phases where I get some piece of music stuck in my head and when I do it's incredibly detailed. I can pick out individual instruments in an orchestra and hear reverb. It can actually get so distracting that I have to play a trick to get it to stop. I need to find a piece of interesting music that I've never heard before. I can play that enough times to "drive out" the other one but not enough to "light up" the new one and I'm fine.

As a kid it was obvious that this was not something everyone did and I thought I was special. It turns out that beyond being an interesting curiosity I haven't found any actual use for it. Too bad. I still find these differences really interesting.

As an aside, I'm also one of those people that's terrible at remembering names and faces. I often completely forget someone's name and face within minutes of meeting them. I've started using Anki to help with it. I make flashcards of all the people I'm supposed to know and run through them every night. It's a hack that works well enough that (some) people think I'm one of those people that never forgets a face.