Sorry, ET lovers: That "fossilized thigh bone" spotted on Mars this week was really just (can you bear the tension) a rock, NASA says. "No bones about it!" writes the agency on its website. "Mission science team members think its shape is likely sculpted by erosion, either wind or water." The Houston Chronicle calls NASA scientists "space agency killjoys" for explaining that any life in Mars' history likely existed at the microbial level, owing to a lack of oxygen to support complex life forms. And CNET notes that the rock was too crooked to be a thigh bone anyway. But today's alien enthusiasts aren't the first to dream: Astronomers claimed to see canals on Mars in the 1800s, and fans interpreted a "face" amid the light-and-shadow play of a 1976 photo of the planet's surface, Space.com reports.