A marlinspike is a classic tool used in marine ropework and often found with folding rigging knives. It is designed like a sharp metallic cone. It is polished and may have a sharp, flattened, or rounded point. The sharp variety is quite rare though. It is used for various applications, such as unlaying rope or untying knots. This extra tool is one of the main reasons wherefore rigging knives are so popular in the sailing industry.