In March 1999, after receiving part of the meteorite from the British Museum in 1998, a team from NASA's Johnson Space Center examined the Nakhla meteorite using an optical microscope and a powerful scanning electron microscope (SEM), revealing possibly biomorphic forms of a limited size range, among other features. London's Natural History Museum, which holds several intact fragments of the meteorite, allowed NASA researchers to break one open in 2006, providing fresh samples, relatively free from Earth-sourced contamination. These scientists found an abundance of complex carbonaceous material occupying pores and channels in the rock, resembling the effects of bacteria observed in rocks on Earth.