Complex sentence: The body of the grenade is cast iron 8 mm thick, spherical shaped and externally segmented designed to produce between 70 and 80 fragments, a bronze-like stick (which is the igniter) is introduced to the spherical body.
Split into simpler sentences: The body of the grenade was cast iron 8 mm thick, spherical shaped and externally segmented designed to produce between 70 and 80 fragments. A bronze-like stick (which was the igniter) was introduced to the spherical body.