While enlarging this picture to put on my web site I noticed an anomaly in the very fine transverse lirae. Upon closer inspection I found that the shell had been damaged and repaired a few times. I don't think the mantle was ever harmed but the front edge of the shell obviously was. Could this be the result of environmental factors or the product of failed predation? Or both?
The following pics were taken through the lens of my microscope. The diameter of the shell near the injury is approx. 6mm.