i found the BEST SEED EVER while i waz bein stupid on singleplayer minecraft it led me to thousands of underground caves in one cave i found a monster spawner and chests one will iron ingots and buckets the other with coco beans more iron ingots and string! when u find a part of the se where it looks like a tnt place go down you will come to a cave go right look round you should find it rough co-ordinates are

x:133.9221569909753n

y:41.62000000476837

z:597.6560144613658

f:0

hope it helps