The story
Named after Steve Mould, science presenter who popularized the effect in a YouTube video.
Etymology from Wiktionary, CC BY-SA 4.0.
Mould effect
Today it means: A counterintuitive physical phenomenon observed with a chain of beads placed inside a jar: when one end of the chain is yanked from the jar and allowed to fall to the floor, it establishes a self-sustaining flow of the chain which rises up into an arch as if being sucked by an invisible siphon. Full definition →