As yoots we used to find shells like this in the woods along tall creek embankments. Those fossils were calcified and crumbled in the hand. This one is a little less brittle. Made by Sampson Mordan of England. Material is sterling and it works as a mechanical pencil. Mechanism deploys telescopically. Circa 1880. Closed length without larger ring 2 1/2 inches. Extended 3 3/4 inches.

  For your listening pleasure, a Conklin All-American Combination (fountain pen and mechanical pencil). This one also includes a feature to remove the pencil part and add a multiple selection colored cap. The system was called Entente. Circa 1930's. The large capped pen/pencil unit is just under six inches in length.