I started my world in TU11, and explored the the last northeast corner around TU25 giving me a strange jungle wall mountain. So my world was fully explored before TU31.
During that time, I built settlements all over the world. There's a patch of ocean I've passed by lots of times and even built a bridge and a house by it and only seen squid in that ocean, even after TU31. When the Aquatic update came out, I flew around my world (elytra/fireworks in survival) liking the new water colors. I landed at that house to get some bonemeal to grow coral in some water. As I was looking through my chests, I heard some guardian rumbles. I looked out the window and saw ink sacs floating on the water and purple laser beams under water. There were guardians in my old TU11 made ocean (dolphins too)! How? My biomes have stayed the same since the shift of TU12 and are still the same now.
Sometime ago, a cartographer was born into my wold selling a woodland mansion map and an ocean monument map. I bought them to see what would happen. The ocean map marked a patch of land by that house with the ocean monument icon. Don't know what to think. Not complaining though.
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