The Leo Triplet, also known as the M66 group, consists of three galaxies located in the constellation Leo the Lion. In the image above the upper galaxy is NGC 3628, the lower left galaxy is M66, and the lower right galaxy is M65. These galaxies are approximately 30 to 35 million light years distant. The galaxies have experienced gravitational interaction resulting in deformations that are most prominent in NGC 3628 and M66. The deformation is readily visible in NGC 3628 by the faint tidal tail extending to the upper left of the galaxy and by the vertical widening of the spiral structure which gives the galaxy a "puffed up" appearance. M66's deformation in its spiral structure is visible in the asymmetrical spiral arms and the very faint tidal extensions extending around the upper right of the galaxy. M65 seems to be the least affected but does display a warping indicating gravitation interaction with its neighbors.
1 http://www.messier-objects.com/leo-triplet/