A gigantic Alien egg, standing 6 metres (almost 20 foot) tall, has mysteriously appeared on the lawn of London’s Potters Field Park today, to celebrate the launch of SEGA’s Aliens: Colonial Marines on PlayStation3,Xbox 360 and PC tomorrow (12th February)

The eerie and entrancing structure can be seen looming over the mayor’s office and Tower Bridge, completely open to the public and guarded by Colonial Marines who were on the look out for the stray Xenomorph that broke free in the area.