LegendBegins said
Booby trap? And copper is green, so it could have been that.
*a panel in the wall slides open and a large metal man the same color as the floor steps out with heavy steps. In a very grated voice it calls out, first in several strange gurtual languages, then something resembling French, then in English*
Metal man: This area is a restricted zone, state your name and caste. You have thirty seconds to comply.