Like a fairy in a jamjar

When I was a university, I had a friend called Tim. He told me that as a child, he assumed seahorses were not real, as they were mostly seen alongside mermaids in picture books. He didn't have cause to alter this view, until a college trip to London Zoo, where he was confonted by a seahorse in the aquarium, and was so staggered he nearly passed out. It was, he said, like seeing 'a fairy in a jam jar.'