These shadowy blocks are literally made of people — at least, one part of people, anyway. For his highly unusual exhibit at the Lisson Gallery in London, Mexican artist Santiago Sierra collaborated with Indian NGO Sulabh International to collect tons of human poop gathered by scavengers of the Untouchable caste in Delhi and Jaipur. He then mixed it with plastic, molded it into 21 giant blocks approximately the length of a human being, and shipped the blocks to the UK. Image via the Lisson Gallery. Blocks of Poop by Santiago Sierra [Art News Blog]