1) ‘E’ and ‘e’
Perhaps pointing to E -> 3 -> iii
2) Missing keys ‘C’, ‘A’, ‘O’, ‘3’
Can be used to spell out CaCO3
3) Protoporphyrin IX
Per Wikipedia:
[T]he component in egg shells that give them their characteristic brown color.
4) Remember CNS/PTE
5) Underlined letters
Unsolved
Multiple elements of the periodic table visibly have their first letter underlined.
Notably the element Hs (Hassium) has its ‘H’ underlined, but it crossed out with a black marker. Rob reacted with a 🤔 to a message which noted this fact.
Excluding the ‘H’ from Hs leaves a set of letters which can spell out the word “MONARCHIES”.
6) Crossed out elements
Unsolved
Xenon (Xe-54)
Caesium (Cs-55)
Lanthanum (La-57)
Gold (Au-79)
7) X=5, Y=6
8) More snowflakes
9) 20 Krona Note
Unsolved
Features many references to famous Swedish children’s author Astrid Lindgren and her well known book Pippi Longstocking.
10) Rock salt
11) Coffee Stain
Unsolved
I suspect we are being trolled and this is a simple coffee stain, but Rob has egged on investigations into it.
12) Lobster
The American Lobster Homarus americanus, maintains stable [amorphous calcium carbonate] throughout its yearly molt cycle
13) Rob and Unknown
Unsolved
We presume this to be a photo of Rob based on the visible armband and baseball cap. He appears to be displaying the ILY sign with one hand and the shaka sign or the letter Y from ASL’s American Letter Alphabet with the other.
His lower half appears to be merged with some partial concentric ovals, vaguely resembling the shape of an eye.