Anyine with knowledge in keys can possibly tell if this is an older key or a remake. The white is seems to be salt crust as it was found along the beach.
at about 10 inches
TTACH]
Look to the sides if you can see any "edges" that could show if it was cast in one piece.
At a first glance I'd guess early 1900's or late 1800's, but don't take my word for it. I like the design!
Older ones were often made by the blacksmith and soldered together I think.