Derek Moulton (Fellow and Tutor in Mathematics) has published a study that explains how the interlocking shells of bivalve shells are created.
A striking feature of bivalved seashells is that the two valves fit together perfectly when closed. The two sides meet with no gaps or overlaps, despite the fact that each valve may present ornamental patterns of varying regularity and size; and they continue to interlock throughout the shell’s development, even when the shell edge becomes irregular because of injury or other environmental influences.
The study by Derek Moulton and his team, published in the Proceedings of the National Academy of Sciences, explains that this feature – seen in the shells of brachiopods and of bivalve molluscs, such as clams, mussels, oysters and scallops, which derive from a common ancestor – provides a protective role against predators and environmental events. But although this functional advantage is understood, it has not been known how the interlocking feature is formed. By creating a mathematical model of shell growth, the team have been able to explain how geometry and mechanical forces combine to generate the shells and to provide insight into the biophysical processes involved.
You can read the full research article here.