So the wood panels lay on top of the metal beams, it's a bed frame but I noticed these spots on the metal and rubbed them off and smelt like rotten eggs please let me know 😑
This was already answered hours ago by another one of our more experienced users, when you asked this under a different username:
Honestly, it appears to be simple iron staining. Appears black on wood, white on zinc coatings. Simple reaction of carbons in the metal and tannins in the wood. Although it is activated by moisture, it is not a mold, nor harmful.
Yes, the wood (first picture) is iron-stained as NPM says, although the chemists say that simple mechanical action (rubbing) is what caused it.
The 2nd picture to me shows corroded galvanized steel (steel elecotplated with zinc). The outer white circles are white rust (corroded zinc), while the inner disks are exposed (and possibly slightly corroded) steel.
The two process are probably related by the wood slats rubbing on the galvanized steel frame when you move in bed etc.