Step right up and let me tell you about the latest all-purpose, cure-everything household tool: the horse skull.
Colm Moriarty is an Irish archaeologist. When he was a young boy, his aunt’s home was renovated. Moriarty remembers that the workmen found two horse skulls beneath the floor of the old house. The purpose of their presence was a mystery.
Now Moriarty has a good idea why they were there. He recently excavated two medieval houses near Dublin. He found horse skulls beneath the floor. Why are they there? Sonja Hukantaival, a doctoral student who is writing her dissertation on materials left in household foundations, thinks that the horse skulls served two purposes. The skulls were used in witchcraft to protect or inflict curses and their hollow chambers helped the acoustic qualities of the home. Matt Soniak writes at Atlas Obscura:
Like the horse shoes that some people keep in their homes, the horse skull was thought to bring luck and expel evil. A horse skull foundation deposit, Hukantaival explains, would have ensured fertility, health and a good crop, and guarded against sickness, death, fire and lightning. In the folklore of some countries, like Finland, horse skulls and other foundation deposits were also said to protect against witchcraft when placed at the borders of a house. They could also be used in an act of witchcraft instead of protection against it, Hukantaival says, a deposit secretly placed under someone else’s house would curse the building or steal luck from it.
The other explanation is that they were part of a macabre sound system. The cavities in the skulls amplify and echo ambient noise, and archaeologists think that in some places they were buried under floors to improve the sound when people danced, sang or played music. In the British Isles and southern Scandinavia, presumed “acoustic skulls” have been found in home and churches. In Scandinavia, they also often turn up under threshing barns, where, Hukantaival says, “it was considered important that the sound of threshing carried far.”
-via Marilyn Terrell