The constellation Leo used to have a tail. Ptolemy (the most influential 2nd century astronomer and author of The Almagest) considered the clump of faint stars at the end of Leo's tail as the tuft of the tail. However at some point it became the separate constellation of Coma Berenices. There's a great cluster of galaxies located in there, and it's known as the Coma Cluster of galaxies. Here is a grand
face-on spiral galaxy located within the Coma Cluster.
Image credit: NASA