Thanks to Ling Li, our humble little Window pane shells appear in a fascinating paper about them.
As their common name suggests, these clams are indeed translucent. But they are also quite strong. Ling Li studied why this is so.
In his paper, Ling Li says: The flat circular-shaped shells from Placenta placenta demonstrate high optical transparency in the visible light range while still maintaining mechanical robustness. The optical and mechanical design of this mineralized material system in correlation to its multiscale structural and crystallographical features are discussed in detail through both experimental and theoretical approaches.
Read more in Biological Design for Simultaneous Optical Transparency and Mechanical Robustness in the Shell of Placuna placenta by Ling Li and Christine Ortiz