Body Piles are monster spawners found in Swamps, Sunken Crypts, and Draugr Villages. Body piles spawn all kinds of Draugr. They spawn draugr regularly as long as someone is nearby.
Destroy a body pile by attacking it with any weapon in the game. They can be destroyed from a distance with arrows, even outside their spawning range.
You can detect a body pile’s presence through walls and otherwise out of sight because they all emit the sound of swarming flies.