Cocconeis is an oval-shaped monoraphid diatom which is known for having differing patterns and ornamentation on each valve face, those with and without raphe.  Cocconeis are epiphitic and are very often found growing on Cladophora, a bottom-dwelling green algae that grows in hair-like mats.  In fact, some species of Cocconeis may be considered an "obligate species" of Cladophora, meaning that it present wherever Cladophora is, an that Cocconeis' presence may be used to indicate that Cladophora is or was also present.