Evidence of strange quark matter striking Earth?

sifi writes "A group of researchers have identified two seismic events that they think provide the first evidence of a previously undetected form of matter passing through the Earth. The BBC has the full story [bbc.co.uk]. The so-called strange quark matter is so dense that a piece the size of a human cell would weigh a tonne. I kind of like the idea that the whole Earth can be used as a sort of 'particle detector' - I just hope that I'm not in the way when another one passes through!"