According of pectin, which makes them slippery

According to
Encyclopedia Britannica, the Spirogyra
genus contains around 400 species (2015). These “filamentous algae” are
actually strings of tubular cells with an outer layer of pectin, which makes them
slippery to the touch (2015). These microorganisms live in fresh water where
the “oxygen bubbles” they release during photosynthesis cause them to rise to
the surface as large masses of algae (2015). The genus name Spirogyra comes from the green, spiral
chloroplasts coursing through the center of the cells (2015). These
microorganisms can reproduce sexually (through “conjugation tubes”) and asexually
as well (2015).