By Ari Phillips for Fusion

As the oceans soak up carbon dioxide from the atmosphere they are becoming more acidic. This process, known as ocean acidification, is harmful to marine life in many ways. For one, it weakens the shells and exoskeletons that animals rely on for protection from predators and extreme conditions. This dissolving of shells, which are made of calcium carbonate and rely on a specific oceanic pH, is already starting to happen in parts of the world.

A new paper in Scientific Reports shows that nature might be prepared to fight back against these human-driven changes. Researchers found that mussels grown under projected ocean acidification levels produce “more amorphous calcium carbonate”—i.e. they change their shell composition—as a mechanism to repair the damage created by changes to their environment. Amorphous calcium carbonate is the least stable formation of calcium carbonate.

Dr. Susan Fitzer, from the University of Glasgow and lead author on the paper, said that many marine organisms “need calcium carbonate to produce their shells and exoskeletons from calcium carbonate,” in a statement. “But higher acidity reduces the concentration of carbonate ions available for shell formation and subsequently their shells are becoming more brittle which makes them more vulnerable.”