We report the synthesis of bamboo-like BN nanotubes by annealing amorphous BN powders at 1100°C in an Ar atmosphere. The amorphous powders were obtained after ball-milling h-BN for times longer than 60h. The materials were characterized using high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), elemental mapping, energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Based on our observations, we propose a novel root growth mechanism catalyzed by Fe-based alloy nanoparticles that arise from the ball-milling container.