 ARP81 is a strongly interacting pair of galaxies seen about 100 million years after their closest approach. It consists of NGC6621 to the right and NGC6622 to the left. 6621 is a very disturbed spiral galaxy. The encounter has pulled a long tail out of it that has now wrapped behind its body. The collision has also triggered extensive star formation between the two galaxies. Scientists believe that ARP81 is a richer collection of young massive star clusters than the notable antenna galaxies we covered earlier.