I was on a psylocibin trip at home and decided to put on my blindfold and lay in bed for some introspection and closed eye visuals. For reference, my blindfold consists of a layer of leather with a padded fuzzy lining. It's very thick because it was intended for kink, but I like it because it's comfy and blocks all light.
While laying in bed, I realized I could literally see through the blindfold. I could make out my hand in full color and could even see the ring I was rolling between my thumb and index finger. I could see when I waved my hand and could tell which fingers were up and which fingers were down. I could only really see my hand and whatever I was holding, surrounded by a black aura. It was super cool but bewildering as all hell. My partner was with me and even she was in disbelief.
My best guess is that the psylocibin turned my proprioception into visuals, like a form of synesthesia.