Complex sentence: Other early physical evidence of biogenic substances includes graphite and possibly stromatolites discovered in 3.7 billion-year-old metasedimentary rocks in southwestern Greenland and "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia.
Split into simpler sentences: Other early physical evidence of biogenic substances includes graphite, and possibly stromatolites, discovered in 3.7 billion-year-old metasedimentary rocks in southwestern Greenland. "Remains of biotic life" have been found in 4.1 billion-year-old rocks in Western Australia.