The Floating Pin Trap

A sharp silver glint plunged straight toward a cup of water, and my boots skidded back in sheer alarm—an incoming metal projectile! But wait. It never hit the bottom! I scurried forward, gripping the porcelain edge, spectacles trembling. A thin steel sewing pin was resting flat upon the liquid surface, suspended in midair! Impossible density breach? No! The water dipped beneath its slender body like an invisible rubber skin. Breathless, I plucked a tiny droplet of dish soap on a wooden toothpick and touched the far corner. Sssht! The surface skin ruptured instantly, and the pin sank like a stone! Molecular surfactant disrupting surface tension in a millisecond!