Coloured scanning electron micrograph (SEM) of the diatoms Mastogloia splendida (oval) and Navicula palpebralis (elongated). Magnification: when printed 10 centimetres wide. Credit: Power and Syred / Science Photo Library
Skeletonema is a single-cell organism belonging to the group of algae called diatoms. Diatoms are unique among the phytoplankton in having a glasslike exterior made of silica. Skeletonema is a chain-forming alga and one of the most commonplace diatoms in the marine coastal environment.
Diatoms are microscopic algae composed of separate halves, with delicate siliceous cell walls. They're usually single-celled organisms, though some live colonially. They inhabit fresh and salt waters and are among the most abundant of all phytoplankton.