b) Giger created strange humanoid heads with breathing pipes extending from the nasal cavity. (See Space Jockey's Evolution via Gigers Necronomicon part 2) The Engineer's suits in Prometheus supposed to be the same as the space jockeys from Alien were humans with helmets roughly like the head of the space jockey but were made more like an elephantine due to different aesthetic choices.
|Engineer with helmet in Prometheus|
c) However it seems that in a preview for Ancient Aliens, a stature was shown showing a Ganesh with segmented breathing pipe in place of a trunk, ending in a bowl in such way that it resembled a breathing filter. The thing is presented as a genuine ancient relic, whether it is or it isn't.