A piece of worm-eaten driftwood found at Portballintrae

We found this lump of wood on the shore. One end had been neatly sawn so I assume it was the tip of a spar. I guess it had been floating about in the water for a considerable time before being washed up here on the North Coast.

This find prompts two questions.

These tracks are over a centimetre wide

My first question is: What made the holes?. It is riddled with worm holes and some of these are well over a centimetre in diameter. They are not straight either, but wend their way in contortions throughout the wood.

If it was a worm (or worms), what were they doing gnashing their way through the timber? Was this their food or were they making a nest? Or were they just bored? (Excuse pun) Whatever they were up to they are bigger worms than anything I have ever come across before. Presumably they were sea creatures. Do they live in these waters or did our piece of wood drift in from more tropical seas? If they do live here then I might just change my mind about paddling in the "briny" from now on.

Second question: With such hungry beasties about, how does any wooden boat ever survive such an onslaught? And what about Nelson and his great wooden walled ships? Or had they discovered a worm repellent?

Can you shed any light on these creatures?