Z-239: "Snowballs of Lethal Force"
Z-239 is an anomaly found on the island of Isla Stronga, which was used as a hub for these snowballs for hundreds of years. The snowballs are very dense, and if given a good throw, can incapacitate a person. Around the Hadal Blacksite labs, you can find Z-239 being researched in trey dishes, and have been recently tested as firearm ammunition. Unfortunately, with the recent events of Z-13's containment breach and lockdown of the Blacksite, we cannot access the labs in which they were stored, since most of these labs were flooded. Hopefully you EXP-P members can (If you are brave enough) retrieve these snowballs for further research.
-Mr. Shade