Bacillaria paxillifer
Bacillaria paxillifer is a colonial diatom species in the family Bacillariaceae. Bacillaria paxillifer is homotypic with Bacillaria paradoxa, but B. paxillifera is the correct name.
Bacillaria have a unique form of colonial motility among diatoms. Individual cells slide against their neighbors in a coordinated fashion, allowing the entire structure to expand or contract.