Spidersilk
Herding giant vegetarian spiders for their silk: a plausibility deep dive
Civilizations Thrive in Adverse Environments
Survival when the challenges seem insurmountable
Waterwheels
The mill & the stone in fire & flood
Onagers
Wild Asian Ass (no, really)
Aerogels
From biowaste to feather-light insulators
Pigs
Single purpose livestock with a weird relationship to gender
Horseboat
Transportation combination: getting a horse to power a boat
Transporting Information
Sending messages in low tech societies
Tombs
Burials with dyed bones & deadfall stones
Beetles
Toxic beetles, weird pets, and unusual foods