https://www.bbc.co.uk/news/uk-england-wiltshire-67336495Not up there with the best album covers of all time, but it probably deserves the "iconic" label as it's so familiar.
It's basically the band going, "We're so big, we can do an album with the dullest cover of all time, no title*, no band name and people will still buy it".
*it isn't Led Zeppelin IV, it is untitled