Pics of what appear to be the remnants of the backpack bomb that exploded in the foyer of Manchester Arena have surfaced ... and they show the nuts, screws and trigger used to kill 22 people and injure 59.

You see pieces of the blue Karrimor backpack -- where the bomb was placed, and what appears to be the trigger switch ... found in the bomber's left hand. There's a 12-volt, lead acid battery, the power source.