Differential interference contrast (DIC) light micrograph of Nassula sp. Nassula is a genus of unicellular ciliates that belongs to the Nassophorea class. Like other members of this group, it has a basket-like feeding apparatus (cytopharynx) that consists of a series of microtubules (seen in the photograph). These are designed to allow the organism to ingest and transport nutrients from filamentous blue-green algae. The organisms use this structure to draw individual strands of algae through the cytopharynx and into the body. Magnification: x325 when printed at 10 centimetres wide at its longest edge.