If you refuse to let them go, behold, I will plague all your territory with frogs (Exodus 8:2).
In the 1st century, the Romans were enamored with everything Egyptian. For the Egyptians, amulets representing animals were attributed to deities, and the frog represented the Egyptian fertility goddess Heqet (Heket). This image of a faience amulet in the form of a tree frog (circa 3rd–1st centuries BC) comes from the Metropolitan Museum of Art and is in the public domain.