the octopus is a thing in Detroit because the 8 arms of the octopus represent the number of games needed to win the Stanley Cup way back in the old days before there were 30 teams. Years ago people started throwing octopii on the ice during playoff games. now it's a thing.
the octopus's name is Al. I believe that's after Al Sabotka, the Zamboni driver. Whenever someone throws an octopus on the ice, Al Sabotka goes out and gets it and twirls it around over his head.