What is a trap door fastener called?

It's called a hasp. ------------------------------ a bolt a catch a latch a lock

The trap is "sprung" when it's been set off by an animal.The animal "springs" the trap.It is the same when you "spring" a different kind of trap on a fellow human being.

Extinct Relict

epiglottis

A high pinch point area exists (suicide) between two open doors on the same side.