From The TimeSplitters Wiki

Appearing in all the TimeSplitters games, the Remote Mine has become a well known item. When thrown on a surface or certain items, it will stick to them and wait for the player to activate them, usually by a button press, but in TSFP the player had to take out a switch to activate them. A Remote Mine can also be activated if shot by a bullet or hit by an explosion. Their physical appearance has varied in all the Timesplitters games.