The Solar System existed long before man did, and will continue to exist long after humanity has died out, which can make it strange to consider times from before the Earth and Sun existed. With almost 10 billion years between the Big Bang and the formation of the Sun though, there is a lot of time there to consider, and every now and then we find something from that period. Researchers at Washington University in St. Louis have recently identified two grains of silica (SiO2) as not only being presolar, but from a supernova.
Presolar grains are definitely rare as they had to survive the heat of the early Solar System, but survive they did in the hearts of meteorites which later fell on Earth. To identify the grains as presolar, the researchers look at the oxygen isotopes. The materials that make up the Solar System all have roughly the same mix of isotopes, because everything got mixed together before settling into planets and the Sun. The researchers found these two grains were enriched in oxygen-18, unlike other presolar grains that have been discovered with enriched with oxygen-17. This difference the researchers believe is from the oxygen-17 grains coming from a red giant while the two oxygen-18 grains came from a supernova.
Supernova are among the brightest and most energetic events in the Universe, and it is believed that one triggered the formation of the Solar System. Potentially, these two grains are remnants of that very supernova, but only more study could possibly confirm that.