Torn from the headlines! News about concrete repairing microbes inspired the following Gamma World hazard:
Medusa Microbes: Fast-acting microbes attempt to “repair” their target by replacing organic materials with calcium carbonate. Moderate Perception check to notice minor petrifications of wildlife and smoothing over of stone-like materials in the area. Any creature starting or ending its turn in the area infected with medusa microbes is attacked by them:
Attack: +8 vs. Fortitude
Hit: Target slowed (save ends).
First failed saving throw: Target restrained (save ends).
Second failed saving throw: Target unconscious (but not prone, save ends).
Third failed saving throw: Target dead and permanently petrified.