I was building a massive base with stone bricks in creative, and when i went to re-build an area i noticed that ALL the stone bricks on that side of my castle had turned into stone brick monster eggs. i realize that a couple stone bricks turning into monster eggs is normal, but i had over 100 side by side
You probably have been placing monster eggs rather than stone brick (they look the same in the creative inventory; one's on building blocks and the other decoration blocks though).
You can use
/fill
to swap the blocks:/fill ~ ~ ~ ~31 ~31 ~31 minecraft:stone_brick 0 replace minecraft:monster_egg 2
. You may need to mess around with the coordinates in that command or the position you are standing in when you run that command, though.