How would you distinguish that from an ordinary sunken, waterlogged branch?
I'd ask someone with the expertise. Probably toolmarks, but in any case, identification is not a matter of rating from 1 to 5 stars like on Amazon.
Wooden post© State Office for Heritage Management and Archaeology Saxony-Anhalt, Juraj Lipták
“How would you distinguish that from an ordinary sunken, waterlogged branch?”
Or a T-Rex floss pick?
(sorry couldn’t resist)