In Scwarzschild's geometry, wormholes exist at the intersection of black
holes and white holes. Two universes connect there. Theoretically, wormholes
allow for time and space travel. However, they violate the second law of
thermodynamics so our experience of them is limited to software examples.
In FishNtheSea wormholes allow the player to
travel through time and space by clicking on certain living organisms that
inhabit multiple locations or times.