Marine borers attack wooden structures like pilings. They include a wide variety of mollusks and crustaceans that have various ranges and the characteristics of damage they cause varies with species. Damage for some types takes place inside wood where it's not visible, with entry holes established and remaining very small. Other types may be so intrusive that they can penetrate wood protected by creosote. Damage can be extreme and obvious.
Inspectors should limit their comments to visible damage or indications of possible infestation. They should refrain from speculating and recommend inspection by a specialist if they suspect damage that they can't confirm. To learn more, read the following article: