Through the smeary little window Gideon could see that Response had opened up. Harrow continued, joylessly: “The door shuts in response to—as far as I can tell—weight and motion. I didn’t test precisely how much weight, but it’s around thirty moving kilograms. I have, at this point, sent around ninety kilos’ worth of bone matter into that room.”
The things Harrow could pull off with the tip of someone’s toe bone were astonishing. Three kilos of osseo for Harrow could have been anything. A thousand skeletons, crammed and interlocked within Response. Seas of spines. An edifice of cranium and coccyx. Gideon just said, “Why?”

Gideon the Ninth - Act Two, Chapter Fourteen