A naval-archive oddity: the turtleback battleship

What is the strangest warship idea encountered in naval archives?

A literal turtleback battleship: an armoured shell over the ship with its turrets placed forward.

This was a literal turtleback rather than the familiar internal armour arrangement. The proposed battleship resembled a floating turtle, with a broad armoured shell covering the hull. Its turrets were placed forward beneath that protection. The unusual external form made it especially memorable among the archival designs discussed.