"Found buried in the back yard, the cord runs underground, along the fence, and was plugged into the house. Seems hollow, something is loose inside when shake it."
"It looks like a junction box that’s commonly used for local connection from buried cable to above ground fixture"
...film container. No mine has this particular imprint on the housing. For pressure you install AP or frog type device under, and pressurize with AT.
They are used all over to prevent damage to ships in general.
We use yokohama fenders while repairing the regular fenders on the jetty.