There seems to be a red and grey wasp balloonogen (balloon protogen) stuck in a doorway/doorframe, half of their massive balloon tail being on your side (your on the other side of the balloonogen/doorway) and the rest of their body on the other side of the door. You couldn't see the rest of their body, you only being able to see their tail. With the door blocking their sight, so they can't see you. If you'd try opening the door, it'd be stuck closed.