A Dear Reader who calls themself Ophistokont made me curious about what this intriguing word might mean. It’s very rare, with only seven Google hits and no entry in Merriam-Webster. Ophi- should have to do with snakes. -stok- calls stoichiometry to mind, having to do with elements. -ont has to do with being. Something that forms the basic element of a snake-like thing, maybe?
I didn’t make that up unaided. Those seven Google hits explain (mostly in German) that an ophistokont is the end of a single-cell being from which its motile flagellum extends. These little whip-like outboard motors have been the object of creationist speculation along the lines that “this is too cool to have evolved by natural selection”: speculation refuted here.