Brown seaweeds get their color because they contain a brown pigment which dominates over the green chlorophyll. They are generally large sturdy plants and don't grow in warmer waters. They are tough and easily withstand lots of wave motion. Brown seaweed can form unique underwater habitats. Some species have bladders filled with air, helping them to float or stand up straight. They often wash ashore in large bunches. All kinds of smaller seaweed species and marine animals live among these bunches. There are around eigthy species of brown seaweed found in the Netherlands. Brown seaweed in the flood mark makes good fertilizer for orache species, such as frosted orache.