Arp 188, aka the Tadpole Galaxy, is a disrupted barred spiral galaxy about 420 million light-years from Earth . Its most noticeable feature is a massive tail of stars about 280,000 light-years long. Astronomers believe that the tail was formed about 100 million years ago by a merger or near merger of two galaxies.
A more compact galaxy crossed in front of a larger one and was partially strung out behind the resulting Tadpole by the gravitational interactions.
Image Credit: NASA / ESA