A live Nile crocodile
We all have that image of some slithering creature creeping into our houses through the toilet. In 1984, a crocodile almost did just that: spotted crawling around the Pont Neuf, a Nile crocodile was eventually found in the warm, food-rich sewers nearby. Authorities captured the creature, which fortunately found a home in a French aquarium.
Merovingian golden bees
No, not the kind from Zelda: these gold-and-garnet bees, which date to about the fifth century, were among five hundred originally found in a Merovingian tomb that was uncovered by a stonemason in 1653. They were passed among the royals, given to the Sun King, and housed in the Louvre and the National Library, until they were stolen in the 19th century. Eventually, the police fished just two of these storied bees from the river... which means that there are likely a lot more waiting to be found.