Londoner Paul Middlewick discovered an elephant embedded in the maps of the London Underground one day in 1988, on his regular commute home from work.
To date, he has found an entire secret zoo of animals, from bats to bottlenose whales.
There are plenty more animals to be found, and people still try to find more each day.
Can you find any secret animals embedded in your city’s metro map?
[via The Daily Triit]