Pieces in the game Battleship are referred to as pegs. The game is a two-player guessing game where each player has a board with a 10x10 grid and a set of ships. Each player takes turns calling out coordinates on the other player's board in an attempt to hit one of their opponent's ships. When a ship is hit, the player places a peg on the board to indicate the successful hit. The game ends when one player has sunk all of their opponent's ships.