Anchor ice is formed on ground stones and other objects at the bottom of running water and thus remains attached or anchored to the ground. Ice crystals are formed and may coalesce or adhere to submerged objects like stones, marine organisms, rocks, man-made structures, etc. Anchor ice is most commonly observed in fast-flowing rivers during periods of extreme cold, in the shallow sub or inter-tidal during or after storms when the air temperature is below the freezing point of the water, and in the sub tidal in the Antarctic along ice shelves or near floating glacier tongues. The flow of the rivers having anchor ice is disturbed because it works as a barrier to the flowing water.