Oomycota

Oomycota, commonly called water molds, is a phylum of filamentous, fungus like eukaryotic organisms that despite their appearance and historic classification are now known to be more closely related to certain algae than to true fungi. Many oomycetes are plant pathogens, including species responsible for potato late blight and sudden oak death, while others live as decomposers or parasites in aquatic environments, and the cell walls of most oomycetes are built from cellulose rather than the chitin found in fungal cell walls.