ecognizing Diatoms: What shapes do they come in?
The wondrous variety of intricate and delicate diatom designs come in two basic shapes, centric and pennate. Centric diatoms may be circular, triangular, or rectangular, but typically have surface markings that radiate from a central area, an arrangement called radial symmetry. Pennate diatoms are elongated with surface markings at right angles to the long axis, an arrangement called bilateral symmetry. Some diatoms link together to form chains or aggregations of multiple individuals of the same species.