Tidepool Tim says,  “Corallina is a unique type of algae or seaweed.  As it grows, it adds parts like a string of tiny beads.  Taking calcium from the seawater it uses this mineral to reinforce its frond structure. Because it has calcium in the growing fronds, this makes it tougher and keeps it from being eaten by ordinary bottom grazers like sea urchins or snails.  When we collect Corallina we often put the clusters into a pail of seawater alone. Over time the Corallina fronds will reveal an entire host of isopods, worms, larval fish, and other organisms that have been feeding and taking shelter in this seaweed.  Very interesting to see how this fauna supports a medley of other marine life.  Our best specimens are supplied attached to horse mussels and small rocks. These look great in any aquarium because of their color and longevity.”