Tabellaria is a genus of freshwater diatoms. They are cuboid in shape, and the frustules (siliceous cell walls) are attached at the corners so that the colonies assume a zigzag shape.
Further reading
References
External links Protist Images Database:Tabellaria - Micrographs of Tabellaria species, but with only T. fenestrata identified to the species level - Tabellaria at algaebase.org