I wish I could tell you what this is…but I don’t know. It looks like it could be a pupal case — the grainy texture at the top curve reminds me of a bagworm’s case — but there’s something very squirrelly about it, such as, if it is a pupa, it does not look like it developed properly. On the flipside, it looks too well-put together and detailed to be bird poo, not to mention too upright. I’m fairly convinced it is an insect sign, as the attachment at the base makes it look separate from the leaf. As usual, all clues, info, answers, etc. are welcome!