If you ever try walking close to the waterline on a sea dike, you surely have noticed how slippery it can be. This slipperiness is caused by gutweed, a green seaweed. Green seaweed gets its bright green color from the dominating chlorophyll pigment. There are more than sixty species found in the Netherlands. All 'higher plants', from eelgrass to trees, find their origin in one-celled green algae. Just like red seaweed, green seaweeds degrade more rapidly than brown seaweeds. They make a good source of nutrients for annual seablite.