One twisted phenomena just to fuel your nightmares!
Rat kings arise when a number of rats or mice (or even squirrels) become intertwined at their tails, which become stuck together with feces, ice, dirt or blood.
No wonder, historically they were often seen as a bad omen, since rats being carriers for diseases.
The first report is from 1564.
The largest mummified rat king (32 rats) was found in 1828 in a miller’s fireplace at Bucheim, in Germany.
The most recent monstruosity was found in Estonia in 2005.
However here, in 2011, a user claimed to have a rat king in his backyard.
You can view some rat kings in Mauritianum museum in Altenburg, the Museum of Zoology in Tartu, Estonia and in the Museum of Nantes.
Here you can find some useful resources to deepen your knowledge about this phenomena: