So, it makes this beeping noise that you can hear from across the map. My friend said it's the antlion alarm noise from Half Life 2.
I call it the "angry rhombus", because I do not know if it has an official name. It was wandering in the fenced zone just past the river with radioactive barrels in it.
It opens up.
Fair to note that this was before midnight.
Sorry that I didn't have more screenshots or think to record this. Anybody else run into this freaky box?