Articulated red coralline algae grows in intertidal and subtidal coastal areas such as the tidepools where these photos were taken. The name "coralline" refers to the fact that these coral deposit calcium carbonate in their cell walls creating a hard outer covering that bears a resemblance to coral. This calcification of the thallus serves primarily to deter most herbivory as the hard material is extremely difficult to bite or chew.
Erica Lauer Vose 