Nope. They are actual ship wrecks you find and almost always have a treasure chest buried in them somewhere.

Originally posted by Trakehner:

Nope. They are actual ship wrecks you find and almost always have a treasure chest buried in them somewhere.

Nope. Don't think so. Went to where 2 of them should be as shown on the map and found the oval arrangement of stones as I expected.

Shipwrecks on the world generator don't actually indicate shipwrecks, but the chest tied to to shipwreck generation which is the same one used for the stone 'boat' formations. So you are correct, they do indicate the formations of stones as well as actual shipwrecks.

The ship shaped stones do actually have treasure chests but you need to use the Wishing Bone it will ping where there is treasure chests and minerals.
https://valheim.fandom.com/wiki/Wishbone