1. AstrobiologyOU, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK
2. School of Life Sciences, Imperial College London, London SW7 2AZ, UK
3. Department of Geography, Durham University, Durham DH1 3LE, UK
4. Earth and Environmental Science Department, Botswana International University of Science and Technology, Palapye 10071, Botswana
5. School of Geosciences, University of the Witwatersrand, Johannesburg 2001, South Africa
6. Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye 10071, Botswana
7. Department of Biological, Geological, and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
8. Department of Geology, University of Johannesburg, Johannesburg 2006, South Africa