The structure of ice grown in water supercooled to temperatures between −2C and −7.5C has been studied and recorded by flash photography. The ice structures formed below −3C are not co-planar with the basal plants of the seed crystals but are split into two, and occasionally more, segments. At temperatures below −5.5C secondary splitting occurs on the major growth segments, the complexity of the structure increasing with increased supercooling. A stepped growth mechanism has been suggested to explain thew observations. The three-dimensional structures so formed are sufficiently, complex to retain unfrozen liquid and so give rise to spongy ice.