Traces of life in basaltic crust refer to signs of past life, including fossilized microorganisms and ichnofossils that reflect microbial activity, in mafic rock. The organisms were once engaged in an endolithic, that is, rock-dwelling lifestyle colonizing open pore space, such as fractures or vesicles, and preserved in situ upon their death. A majority of the fossil remains have been found in subseafloor basalts or ancient oceanic crust (Fig. 1), and only rarely in continental settings. Body fossils are found throughout the basaltic formations, while ichnofossils are almost exclusively found in volcanic glass of pillow lavas.