I generated a new world today, and spawned on an island facing random piles of smooth sandstone and the polished versions of diorite, andesite, and granite. Smooth sandstone only generates naturally in desert temples, and polished diorite, andesite, and granite doesn't generate naturally, so this was weird. Later, I went underwater and found an exact replica of an ocean monument's arches over its entryway. Made out of smooth sandstone. There were even sea lanterns in the right places. And no ocean monument behind it. Whatever is wrong here, it needs to be fixed. I play on an iPad and am writing this report on a computer, so I can't include a screenshot.