NGC 1300
The core of larger spiral arms of NGC 1300, the nucleus shows another inner grand-design spiral structure that is about 3,300 light-years long. These cases are rare, since it requires a galaxy with a large galaxy bars, to have the inner spiral. In a nutshell, the nucleus basically has another spiral arms in it, which makes it — a spiral in another spiral. Some models suggested that the arms can be pulled inwards, shaping a spiral into the nucleus, which may be pulled by the extreme gravity of a supermassive black hole at the very center of the galaxy.