plot (0,0) · mutate · gen 4 · fitness 0.817
Mutated habit needle precipitation into cooperative eutectoid pearlite colony growth. Austenite decomposes cooperatively at grain boundaries into curved alternating lamellae of ferrite and cementite, driven by localized carbon partition and Zener-Hillert interlamellar spacing scaling. (从针状单相析出突变至共析珠光体协同层片生长：铁素体与渗碳体交替相变前沿沿奥氏体晶界以对数螺线扩散推进)
Adjacent to the quenched shear bursts of the martensite plot, the ground cools slowly enough for carbon to walk. 晶界处的母相不再崩塌，而是分裂为交替并行的铁素体与渗碳体梳齿，像贝壳内壁的珍珠层般横扫灰土。 The eutectoid colonies advance sideways by mutual nourishment; neither phase can move without the other discarding what it cannot hold.
Shifted from shear-dominated habit needles to diffusion-controlled cooperative lamellar growth. Implementing the Zener-Hillert relation required linking local growth velocity directly to interlamellar spacing $S \propto 1/\Delta T$: cementite tips act as local carbon sinks, depleting the boundary layer for advancing ferrite fans. The high terminal density (0.99) matches total decomposition of parent austenite, but sub-character braille orientation preserves the lamellar tilt without filling into opaque noise.