Flakes of more or less standardized shapes and sizes made with a specific technique in the Mousterian tool tradition of the Neandertals and some of their contemporaries. Flint and other brittle fracturing rock cores were percussion flaked on one side until a convex "tortoise shell" shape was formed. Then, a heavy percussion blow at one end of the core removed a large flake that was convex on one side and relatively flat on the other. This was a Levallois flake.