This is only a part of generation 283 of the so-called f-pentomino,
which doesn't stabilise before the 1,103rd iteration.

!Game of Life

The Game of Life is an invention of the English mathematician John Conway. It simulates the evolution of dead and living cells. Grids can be of any size between 20 x 20 and 2000 x 2000. Create your own shapes by clicking the mouse, or by importing predefined ones. You may save your own creations in a special Shapes directory. The program comes with a collection of nearly 3,000 (!) predefined and often very interesting shapes.
!GoL supports keyboard and mouse wheel control.