The borings of marine shellfish visible in these columns between II and 19 ft.
Perna and pernocchia meant a shellfish which yielded "nacre" or mother-of-pearl.
This was properly the name of the shellfish (Purpura, Murex) which yielded the famous Tyrian dye, the particular mark of the dress of emperors, kings, chief magistrates and other dignitaries, whence "the purple" still signifies the rank of emperors or kings.
The kima, a great mussel weighing (without shell) 20 to 30 Ib, and other shellfish, are eaten, as are also dogs, flying foxes, lizards, beetles and all kinds of insects.
The western and larger species gathers its food, consisting chiefly of sea-weeds and shellfish, on rocks at low water; but it is also known to eat birds' eggs.