In the Bible, in Jewish liturgy, and in other texts, God is sometimes described as being surrounded by seraphim—often imagined as angels. But, as Benjamin Sommer points out, the word literally means “snake,” and that is probably how these beings were originally conceived:
The image of the seraph as a snake probably comes from Egyptian art. (The term seraf means both “fiery” and “snake”; the idea is probably that the snake’s venom is fiery, i.e., the victim of a snakebite feels a burning sensation.) There are 8th-century BCE stamp seals from ancient Judah that portray the seraph, and the image is similar to a snake common in Egyptian art of that era and earlier.
[Some of these] seals picture basically the same scene portrayed in the book of Isaiah (6:1-7). The text on [one] states that it belonged to a courtier of King Ahaz named Ashna. In light of the similarity between the seal and Isaiah 6, it is worth noting that Jerusalem in the 8th century BCE was a very small town, that both Isaiah and Ashna lived during the reign of King Ahaz, and that Isaiah enjoyed very close connections to the royal court in which Ashna served. Consequently, it is inconceivable that Isaiah and Ashna did not know each other.
Read more on Bible Odyssey: http://www.bibleodyssey.org/tools/ask-a-scholar/seraphs.aspx