All dead snakes, all the time

I spotted this unfortunate little guy on a coastal path, just after someone presumably beat it with a stick.  It was still moving a bit, but I hear snakes can do this for 20 minutes after death, I'm pretty sure it was dead.  Looks like it may have bitten itself in confusion as it was dying.  It's a Common Many-tooth Snake, aka Black-headed Snake.  Jeju is the only place in Korea where they can be found, and were only discovered here in 1981.  There is sand in my ears, but it will come out one day.