Yeep eggs are formed via a mysterious chemical reaction that occurs within Ark City's sewer system. This is where they are found. No one knows how they mysteriously appear in the Egg Cave. Over the course of time, evolution has occurred that has given Yeep eggs an impermeable membrane. As a result, Yeeps don't stink after they are born in the sewers. After birth, Yeeps instinctively know that the sewers are unhealthy, so they surface and are generally found roaming the friendly streets of Ark City.
Yeeps are friendly with Ark citizens; they wouldn't hurt a fly. But unfortunately, Yeeps are to blame for most of the Egg Cave office plumbing and server problems. Sometimes they don't act so smart and find themselves pickled within our plumbing lines. Despite their seeming friendliness, they have the uncanny ability to make a person feel very awkward... at the Egg Cave offices, Yeep conspiracy theories are discussed regularly.