Described is a device for inducing crystal nucleation in a crystalliser. The device comprises a vessel for fluid and a surface abrader, wherein the surface abrader is configured to abrade a surface within the vessel to induce crystal nucleation. The friction of the abrader against the surface within the vessel creates nano-sized particulates which induce crystal nucleation. Crystal growth can then take place in the crystalliser. Also described is a crystallisation apparatus comprising the device and a crystallisation process using the device or similar. The device is significantly cheaper and more reliable than known ultrasound devices and facilitates the separation of crystal nucleation and crystal growth. The device also enables the avoidance of the use of seeding as a source of secondary nucleation.