Item from deaths-end by
Trisolaran probes — mirror-perfect quicksilver teardrops, each capable of destroying an entire human fleet, and the weapon that ends the Deterrence Era.
Droplets are wrapped in a shell of strong-interaction material — particles bound by the strong nuclear force rather than electromagnetism — making them effectively indestructible to any chemical or kinetic weapon humanity possesses. Originally taken as gifts of goodwill, the droplets annihilated almost the entire Solar Fleet in the Doomsday Battle. By Death's End, nine droplets have been hidden behind the Sun for the entire Deterrence Era; minutes after Cheng Xin's investiture they emerge and destroy the gravitational-wave antennae. Two later attack Gravity and are themselves destroyed by the Blue Space crew using a 4D space pocket.
Each droplet is a smooth teardrop roughly the size of a small truck, surfaces so perfectly reflective the eye loses depth — looking at one is like looking into a hole in space. Capable of impossible maneuvering: 90-degree turns at full speed, instant acceleration, no exhaust. Colored only by what they reflect.