Snakes on coins was an old idea, this one is from Roman Egypt, AD 130:

Hadrian - Roman Provincial Egypt Bronze Obol - Cobra
Laureate head right
AVT KAI TPAI ADPRIA CEB (Emperor Caesar Trajan Hadrian Augustus)
Cobra erect with head left, hood spread, crowned with horns and disc.
L-ID (year 14) in field
Struck: AD 129-130, Alexandria, Egypt
Size: 20mm
Weight: 4.94gm
Catalog: Milne 2249
The cobra was a symbol of royalty and divine authority in ancient Egypt.
