I have several.
They are made from oak logs that have sat in a bog for thousands of years. The wood becomes mineralized. But, being a hardwood pipe for all intents and purposes, they can char easily if you’re not careful.
The wood itself will dull tooling somewhat faster than carving a briar, due to the mineral content.
Several years ago when I first looked into these, the prevailing wisdom was to keep any cake out of these, or they could crack. Treat it like a Meerschaum… I haven’t found that to be the case. In fact, a cake is necessary to keep the chamber from charring so easily IMHO, as with any hardwood pipe. To paraphrase Capt. Willard from Apocalypse - The BS piled up so fast on the interwebs…
They are cool looking. There is a musty, boggy taste at first.
The cost of getting equipment out in a bog somewhere to yank these out, the extended dry time which requires close monitoring so the wood doesn’t crack, and relatively low yield of blocks is what drives the price up.