i would suggest that the metal oring is an indication of where the floor is ‘pre cut’ as an access to the top of the engine, but the flooring was not cut by the factory - you cut it yourself if you ever need to.
my bed is over mine, and it’s carpet, and no oring...I’ve never had a need to really look any closer than that, tho
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )