That is the Seeker armour. Something that an artist at 343 was able to model and texture with a straight face, and somehow got approved to be a canonical armour set utilised by the UNSC.
someone fixed itWhat is that abomination on the right
It pretty much symbolises everything wrong with halo.
Why does the visor stretch into the sides
Why are the sides so far out?
Why is the visor concave rather than convex like on the rest of the helmets?
Why is the front part look like a platypus's mouth?
I honestly think this is a bug. They drew up a helmet and modelled it, but when importing it into the game, the parameters got shuffled around a-la Vinesuace ROM corruptor and this look is the result.