Underwater, Overwater
It appears that nowadays, it isn’t that uncommon for individuals to just come across explosives by accident, which is a cause for considerable concern. What you’re seeing here may appear to be some sort of protective casing, but it’s actually an underwater mine: not under the sea.
Fortunately, we believe such a mine would most likely not be a danger at this time. If only because it takes more than merely touching it to set one off. Still, it’s probably best to leave it alone for the time being.