The follis (plural folles; Italian: follaro, Arabic: فلس, Fels) was a type of coin in the Roman and Byzantine traditions.
It has also been suggested that the coin was named Follis because of the ancient Greek word "φολίς" meaning a thin layer of metal (cf.
Latin folium, "leaf") which covers the surface of various objects, since originally, this coin had a thin layer of silver on top.
For example, in Seaton Down, Devon, England, near the site of a second- to third-century Roman villa and fortifications, 22,888 folles were found in 2013.
[3] Between 30,000 and 50,000 exceptionally well-preserved folles from the first half of the fourth century were discovered in the sea near the north-east shore of Sardinia in 2023.