Ankheg Shell

The Ankheg shell is an item which can only be sold to Taerum Fuiruim in Beregost for 500 coins as long as they don't make the agreement that he will make one set of Ankheg plate mail. Ten days later it is ready and the option is no longer available to sell any shells.

In-game description
"The Ankheg is a burrowing insect-like creature between 10 and 20 feet tall, found mainly in forests or agricultural land. They are covered in shells made out of a substance called chitin which is extremely tough and very light. The size, the weight and strenght of the shells make them highly sought after in many situations, including the creation of armor."