the seed only generates what can be naturally generated. I used a super flat ocean one, so all that will generate is a vast void of noting but water, sand, stone, and bedrock. I did not toggle the layers, so basically, what a player builds is not encrypted into the seed, so the re-using a seed will only generate the land from when it first was created. So if a seed was used for a map, and you used it, you would only get what was naturally there, ok?