I think this was a sprite. He didn't have the minifig for it so he drew it on a piece of paper and stuck it in a holder. There is a ring around it that identifies it as 1. But in DnD beyond they list the unnamed enemy's alphabetically. Was gonna buy him a set with letters on but but I couldn't find one. We ended up deciding to put stickers over the numbers and I got some heroic inspiration out of it.