Bacillaria paxillifer syn Bacillaria paradoxa, Nitzschia paradoxa
These cells form unique colonies in which the cells slide back and forth against each other much like a carpenter's rule, a common name given to this species, and then retracting to tabular, ribbon arrays. They are 70-115µ long and 5-6µ wide appearing rectangular in girdle view and linear lanceolate in valve view. Collected from the Ross Sea 2005. See Horner in Taxonomic References.