Along, narrow glacially-eroded inlets in which the sea extends inland are known as cirques. fjords. tarns. paternoster.

A long, narrow glacially-eroded inlets in which the sea extends inland are known as fjords. It is a deep, narrow and elongated sea or lake drain, with steep land on three sides. The mouth of the fjord is the opening toward the sea and is normally shallow. The fjord's inner part is the sea bottom. When the geological is wider than it is long, then it is not a fjord.

Lobster is the answer. It can be split evenly down the middle