The Apollo crews left about ninety-six bags of urine, faeces and vomit on the surface, because mass going up was worth more than dignity.

Every bag left behind was a bag's worth of rock that could come home instead. Whether anything in them is still viable is a genuine scientific question — freeze-dried bacteria that survived fifty years of vacuum, radiation and 300-degree temperature swings would say something useful about how life might travel between worlds, and somebody will eventually go and look.