<p>For three decades, solidification of water with biomaterials, such as cellulose nanofiber, cellulose nanocrystal, chitosan, and collagen, has been widely studied for fabricating aerogels having three-dimensional pore structure of these biomaterials. However, experimental results, necessary for understanding and control of such fabrication processes, are not sufficient. We have hypothesized that two-dimensional measurements for dendritic ice in thin water layers with the biomaterials will provide valuable results to comprehend and improve these processes. We conducted experiments on the solidification of water containing cellulose single nanofiber, cellulose nanocrystal or sodium carboxymethyl cellulose in a narrow space between two cover glasses. Successive images of ice/water interface were captured with a video camera attached to a microscope. The temperature was measured with an ultra-fine thermocouple inserted in this space. It was found that the interface temperature of each mixture was slightly lower than that of deionized water. This decrease in the interface temperature caused by the biomaterials was less noticeable than the freezing point depression of sodium chloride in the identical mass fraction. We discovered alternating periods: one includes the attenuation of ice growth with interface-tip blunting, and another includes the enhancement of ice growth with interface-tip sharpening. We tried to explain these phenomena by the migrations of both aggregates and individuals of cellulose nanofibers and water molecules, based on the analogy of freeze casting of cellulose nanofibers.</p>