Requiem flying squid
From Halopedia, the Halo wiki
This flying squid was an alien lifeform living in the jungles of Requiem. It was to be prominently featured as ambient life in Halo 4 during the level Infinity, but the idea was cut before the game's release. It can be seen in various concept art and in the Halo 4 E3 2012 demo build. The concepts had mostly been drawn by Nicolas Bouvier and Paul Richards.