The Foug M1916 Lemon Grenade, named for its distinctive lemon-like segmented exterior, is an iconic French hand grenade from World War I. 

It was activated using a simple time fuse mechanism. To operate, soldiers would remove a cap at one end of the grenade, revealing a friction igniter. Upon pulling the igniter's string, a delay would initiate, giving soldiers a few seconds before the explosion. 

This type of grenade was typical of the era, reflecting the balance between manufacturing efficiency and battlefield effectiveness. Its design influenced many subsequent grenade models due to its practical and effective fragmentation.