Chara algae are ancient plant organisms that are commonly found in freshwater reservoirs and occur, though more rarely, in water bodies with salt water. An unusual feature of this type of algae is the huge size of individual cells, which can reach up to one mm in diameter and up to several centimeters in length. This feature makes Characean algae a unique subject for the study of intracellular signals, which are associated with the appearance of signaling molecules in some parts of the cell (for example, when they are touched or illuminated) and their propagation to other cell areas. As these intracellular signals propagate, they cause various physiological responses, including changes in photosynthesis and respiration.