Is the Serpent Mound, really a depiction of a serpent?

This is the Serpent Mound in the US, that everyone (Including Graham Hancock, who's documentary these pics are from) has assumed that this is a depiction of a snake, but what if it's not, what if it's a sperm?
If you look at the head, it is supposedly opening it's jaws onto an egg?
But look at a sperm under the microscope and this looks remarkably similar.
Maybe, when the builders built this, they were trying to, symbolically, rebirth the sun (which is the egg) by fertilising it with the seed of the Earth, fertilising it on the summer solstice, to ensure it's rebirth in the spring?