Last year, a strange little green rock from space was found in Morocco. The discovery was given the not-so-sexy name of NWA 7325 and was filed away for study. Enter Earth and Space Sciences professor Anthony Irving, from the University of Washington. This guy is an expert on all things meteorite, and he thinks that NWA 7325 is Earth's first Mercurian meteorite, all the way from the closest planet to the sun. Here's how Professor Irving thinks things went down.
Some time ago, huge asteroid impact takes place on Mercury, and blasts NWA 7325 off of Mercury's surface and out into space. The chunk of rock circles the sun for millions or billion of years, and eventually, it intersects Earth's orbit and lands in Morocco, and someone picks it up.
If this sounds far-fetched to you, here's a bit of evidence courtesy of Professor Irving. First, the rock isn't from Earth. Or Mars. Or an asteroid. We can tell that this is the case due to its composition along with trace gasses trapped inside the rock. That said, it isn't yet certain that NWA 7325 is from Mercury. It could be from some other place very similar to Mercury. More study of the meteorite — and of Mercury — is needed before we can be certain.