That's a snake. The head is at the top, the yellow-spotted end being the tip of the tail. The yellow spot might cause predators to attack the snake's tail instead of his head.I couldn't identify it but after I published the picture it was identified by Levi Gray, a grad student at the University of California at Davis, as Leptotyphlops goudoti. Species in the genus Leptotypholops are known as Blind Snakes. A book gives one English name for it as Goudot's Thread Snake, though Black Blind Snake is another name published for it.
Leptotyphlops species are non-venomous, blind snakes found throughout North and South America, Africa and southwestern Asia, with about. 86 species being recognized. Otherwise our species seems to be little known.
By the way, my impression is that with the arrival of the wet season snakes are becoming easier to see and species other than Speckled Racers are emerging.