The Hypatia stone, found in western Egypt in 1996, is believed to have formed about 28 million years ago in a meteorite impact. In 2013 it was confirmed to be of extraterrestrial origin and possibly the first sample of a comet nucleus. Now Georgy Belyanin of the University of Johannesburg in South Africa and colleagues have found compounds including polyaromatic hydrocarbons and silicon carbide associated with a nickel phosphide compound not found in the solar system before. Other facts supporting the other-worldly origin of the stone include ratios of silicon to carbon opposite to those of the Earth, Mars or Venus, but consistent with interstellar dust, and mineral grains that contain phosphorus and metallic elements not in the ratios expected. The Hypatia stone challenges the generally accepted view of how the solar system was formed and the study of its history continues.

Further reading
• G Belyanin et al. 2018 Geochim. Cosmochim. Acta 223 462.