Shakri cube

The Cubes were cubic boxes used by Shakri in order to confuse the Human race. Each cube had their own features when they were activated for a total of forty-seven minutes after a dormant total time of a year.

Biography
The cubes arrived on Earth overnight and were investigated by UNIT to be found as dormant and unmoving. The Doctor wanted them to be vulnerable, but nothing happened until after a whole year.

While in his kitchen, Rory found a cube opening and closing at the sides. Amy found a cube that began to move. She touched it and spikes stabbed at her palm. While playing on a Wii, the Doctor found a hovering cube, which fired lasers at it. Brian found his shuffling across the table in front of him.

While visiting UNIT headquarters, the Doctor and Amy were told by new leader Kate Stewart that all cubes had their characteristics. One in captivation caused mood swings, one breathed fire and another looped music.

The cubes then glowed a countdown. The Doctor watched one as it reached 0. The cube opened to reveal nothing. But when exiting and looking at one of the UNIT consoles he discovered people around the world were being affected by some hidden phenomenon. He then realised, while he suffered a pain in his chest that it turned off hearts.

A second wave of cubes were to be commissioned to the Earth, but were stopped by the Doctor while on the Shakri Ship. (TV:  The Power of Three)