I will have to remember which video I was watching, so the exact details are a bit fuzzy, but a person had visited somewhere where butterflies (I think monarchs) were being studied. At one point the person studying the butterflies opened a caterpillar and pulled out wing buds

I’ll try to find the video because it was interesting and I’d like to back up my words

Edit: I’m sorry, I looked over my history and I can’t find it. I think it was a larger caterpillar, an instar or two away from metamorphosis