In WW1, grenades were in an ever-evolving state as both sides competed for the the right type for the right job. In 1917, the Germans introduced the M17 Eierhandgranate "Egg Grenade", which as its name suggests is small and egg shaped with a smooth exterior with a single fragmentation band, which also allows for a better grip. An earlier version was introduced in 1916 that had a smooth body with no fragmentation band, but troops complained about the grenade being hard to grip and it slipped easily. So the M17 was officially called the M17 N/a - Neuer Art or New model.
Below is an example of the M17 with the M16 percussion igniter which had a 5 second delay. The average soldier could throw the M17 about 40 meters. This grenade had an explosive filling of gunpowder, aluminum and barium nitrate. Typically on the M17 N/a you will find makers marks on the bottom of the grenade as well.