Lucky stone

A lucky stone is the otolith of a freshwater drum. They are quite big. In ancient times, they have been worn as protective amulets and were thought to ward of sickness. Lucky stones wash up on beaches along the Great Lakes, especially Lake Erie. They've also been found at archaeological sites.

L stones

The "L stones" come from the left side of the drum. According to George R. Spangler, the L-shaped groove is called a "sulcus". It is close to neuromast cells in the inner ear.

J stones

The "J stones" come from the right side of the drum. Not much is known about them, though.

References

1. Hudson, William (2013). "Lucky stones". neoNaturalist.com. Retrieved 2018-05-12.