Steel that has been in Salt Water for a long time will start to flake and fall apart after it's been exposed to air.
We used to soak the old Anchors we found in a Lye Bath for six months to a year.
Then apply several heavy coats of paint. This prevents further deterioration in the future.
Congrat's on the save of the anchor. It is really a nice piece. There is a product called Gemplers. I don't know if you have heard of it, but it is a product that treats iron from the inside out and stops the rusting process. There are some Utube videos on this product of interested. I have used this on some of my CW relics and was pleased with the results. This will turn the iron black, but it gives the iron a nice sheen when treated and you'll be able to see a lot of detail on what has been treated. I am in no way affiliated with this company, just a satisfied customer. Check this out and see what you think.
Cool recovery. It appears to be a solid iron-stocked anchor, essentially to ‘Admiralty Pattern’. The name arose because the design was adopted by the British Admiralty in 1852, although they were by no means the first user and the configuration is borrowed from much earlier designs. This is a traditional Admiralty Pattern anchor:
These are sometime improperly called “kedge anchors”, “fisherman’s anchors”, or “Herreshoff anchors” but those are generally smaller, with a thinner shank to make them lighter and easier to handle, as well as having smaller flukes.
Stockless anchors came into use in the 1820s and ships began switching to stockless soon after, but older ships continued to use Admiralty Pattern long after that. The Royal Navy didn’t begin switching to stockless until 1885 and fully adopted them by around 1903. I don’t think it’s naval though. They tend to be plain and utilitarian in design, without any ‘decorative’ embellishment, and of heavier construction than yours.
Other than that, it’s difficult to put a date to it or determine what kind of ship it came from, except to say probably from a small/medium-sized vessel. Admiralty Patterns were generally used as temporary anchors for short-term mooring/berthing, or to stop and hold a vessel in the water.