As sea water freezes, needles of ice form and grow into platelets which gradually produce a slush at the sea surface. As ice forms, the salt remains in solution, increasing salinity and further lowering the freezing point of the water. Depending upon how quickly the ice freezes, some salt may be trapped within the ice mass, but it gradually is released.
Pancake ice are rounded sheets of sea ice that become abraded along the edges as ice masses collide.