A trap (or 'mark') is achieved when all the adjacent intersections of a piece are occupied by opposing ships. Note that the kraken cannot be one of the pieces used to surround and a surrounded group is not considered trapped. There is no capturing in Mur. When a ship is in a trap, the owner of the ship must remove it from the board. The withdrawn ship then becomes an ‘off-board’ piece. A player may have any number of off-board pieces at any one time. Any off-board piece may be entered back into play by simply placing it back on the board on any unoccupied intersection. However, when the kraken is trapped, it is not placed off the board; it is placed upon the center intersection of the board as a reset (see completing the game). Note that it is possible to trap two ships simultaneously as long as the ships are alone and not part of a group.