Marlinspike

A marlinspike (/ˈmɑːrlɪnspaɪk/, sometimes spelled marlin spike, marlinespike, or [archaic] marlingspike) is a tool used in marine ropework.

Shaped in the form of a narrow metal cone tapered to a rounded or flattened point, it is used in tasks such as unlaying rope for splicing, untying knots, drawing tight using a marlinspike hitch, and as a toggle joining ropes under tension in a belaying pin splice.

They are usually made from iron or steel, whereas fids, similar in shape and function, are formed from wood or bone.

Historically a separate tool, the marlinspike is integrated in specialized versions of folding rigging and pocket knives.

Marlinspikes are used: Marlinspike derives from the practice of "marling", winding small diameter twine called marline around larger ropes to form protective whippings.