Teredo just ate through that wood samples as if there was nothing there.
From the poseidonsciences.scienceblog.com
Teredo worms inside an infested wood being collected in Batan, Aklan Province, Philippines.
From the poseidonsciences.scienceblog.com
In tropical waters, without anti-teredo treatment, the life expectancy of a ship is about 10 years.
From the newsobserver.com
The Athenian trireme fleet needed protection from rot, decay and the teredo so this new source of tar was valuable to them.
From the en.wikipedia.org
For the uninitiated, wooden boats require some sort of sacrificial material attached to the keel, designed to keep boring teredo worms at bay.
From the newsobserver.com
It's strong yet soft, smooth and light, hardly shrinks and is pleasant-smelling thanks to an oil, methyl eugenol, that's hated by teredo, the termites of the sea.
From the time.com
More examples
Typical shipworm
A marine borer that damages untreated wood by drilling holes in it.