Red algae do not contribute towards:

Explanation

The multicellular body form of red algae is commonly composed of complex interwoven filaments that are delicate and feathery. A few red algae are flattened sheets of cells. Most multicellular red algae attach to rocks or other substances by a basal holdfast. Some red algae incorporate calcium carbonate in their cell walls from the ocean and take part in building coral reefs along with coral animals. Red algae do not contribute to making fertilizers.