The interwebs are all atwitter at the alien thigh bone found on Mars by the Curiosity rover. I’m sure this is old news by now.
More likely than not it is actually a volcanic bomb formed as molten rock thrown from one of the Martian volcanoes or impact craters cooled while flying through the air.
One wishes they would send Curiosity over to run an analysis on it. If it had the chemical composition of Martian rock, one could more forcefully argue against it being a fossil.