The pictures of the Budweiser & Spam cans at nearly 4000 and 5000 meters depth respectively are astonishing: http://oceanexplorer.noaa.gov/okeanos/explorations/ex1605/lo...
EDIT: Pure speculation, but given remoteness and how well preserved they are, I suspect they're the litter of commercial fishermen.
If this reference[1] is historically accurate, then the Budweiser is from circa 70s or early 80s, a period before I was conceived and probably predates what would have been a convenient Born On Date reference that Anheuser-Busch made popular.
The relevant production stamp on the Spam can reads F01031, and if we were to trust this reference[2], then it decodes to plant location F (199N cross-references to a plant in Fremont, NE[3]) manufactured January (01) 3rd (03), with certain ambiguity in the year code 1. Observe Hormel Foods label, so this comes from after 1993 name change as suggested by this brief history[4], leaving 2001 or 2011. The styling of 25% LESS SODIUM label cross-referenced against this guy's collection archive[5] factors out 2011, deductively pointing to 2001. Other clues considered include rough time period for when Spam Stuff marketing was a thing, and lack of BEST BY date which is included on the bottom of Spam cans manufactured today.
[1] https://i.imgur.com/P3cyai6.jpg
[2] https://www.usaemergencysupply.com/information-center/self-r...
[3] https://www.fsis.usda.gov/wps/wcm/connect/a5c2b5c8-92e0-4565...
Worse still, if that inter-historic era never occurs due to the persistent presence of intelligent machines.
At that point, all bets are off, as to whether even remnants of our pollution might remain, in the face of pervasive systems engineered to keep ecosystems free of the detritus of human civilization, and automatically recuse themselves from pristine areas that require no further stewardship.