I've seen my snowflake do the writhing snake ball 2-3 times when I give it an oversize piece of shrimp. It freaks me out!!!
Looks like one of those snake breeding balls you see on TV, but just one critter involved. Eel used its balled-up body to rip the food as it pulls its head backwards. I'm telling you man, you will NEVER look at an eel that same way after seeing that in person.
Most of the time it prefers to grab, retreat, bang and swallow. Makes perfect sense when you think about eels being dragged out into the open water after snatching a strong swimmer prey. If you have your tail anchored you can't be dragged out, and banging the prey on coral etc. is certain to render your meal motionless.