It suddenly occured to me to run back east and get the backpack full of potentially useful things. Inside it had three bags of generic-brand chips, two bars of what was presumably some kind of food, and a PDA. The screen on the PDA was cracked; I tapped a few of the buttons but got no response.
Walking back into the glowing chamber, I looked at the ceiling. It looked perfectly smooth and dome shaped. I tried rotating the pyramid to the left a few times, but nothing happened. Finally I braced myself for potential pain or traps, and set the crystal I had found in the campsite (which looked to be made from the same material as these ones) down between the pyramid and square.
Predictibly, pain followed. An icy spike shot up from the ground and went through my leg. More spikes came down in the doorway, barring me in. It hurt a lot. The leg one, not the door spikes.




Inventory

(note: the spike only came from the bottom because it would've been hard to make it come from the top.)