Identifying images on flat buttons

Hey guys! I started going through all my buttons that I've found over the past year and I came across 3 flat buttons that when I put a flashlight on them and go side to side, I notice "something" but I can't quite make it out and it's driving me crazy. I used navel jelly for like 20 seconds to remove any gonk which seemed to help a little but I don't want to use it too much as I'm afraid of completely destroying whatever is there...any tips or ideas as to how I can recognize or make the image stand out a little? Here's a pic of one of the buttons...there's def something there!! Driving me crazy lol.