This is an image of stratigraphic levels in ancient seafloor rocks in southern Sweden, one of the locations where the authors studied the rock. The red line marks the time of the Ordovician Meteor Event. At that same line, analysis of the rock shows an abundance of L-Chondrite grains that drifted down to Earth after the OME. The nature of the limestone changes, too, indicating that it formed during time of lower sea levels, as the poles froze and the oceans dropped. Image Credit: Birger Schmitz, Lund University