For everything there is a prototype - even toy train tunnels! Here is a picture of a tunnel on one of the old railroads in Costa Rica. It goes right through that bump of a mountain - just like the accompanying pic of the toy train tunnel. Why they didn’t go around that hill, I don’t know - but there it is - there is a prototype for just about anything! If you have similar unlikely prototype pics, feel free to sharethem here in this post.