Borer

The borer was a species of Safeholdian shellfish which attached itself to the hulls of ships or the timbers of wharves by boring into them, much like similar species on Earth.

There were several types of borers, the most destructive of which actually ate their way steadily deeper into a wooden structure. Borers and rot were the two most serious threats (other than, from fire) to wooden hulls. (OAR)