I had an invisible sea monkey once. He was insanely good at playing Hide and Seek. He wanted to join a professional Hide and Seek team. I tried to help him, but I could never get an agent to take me seriously. I'd point at him and say, "Look! He's an invisible sea monkey! See?"
The 17th rejection was the last straw. He left a note, written in invisible ink, and then vanished along with one of my invisible bathyspheres. I was pretty upset. I had left a perfectly good grilled cheese sandwich in that bathysphere.