iOS_Minecraft, a friendly, well known person in the community is great at making concept videos for Minecraft Pocket Edition. A few days ago, he showed off his latest concept of ocean monuments in MCPE.
— Minecraft Wikipedia
Ocean Monuments were introduced into Minecraft 1.8 on the computer version, and of course, not yet implemented into the mobile version of Minecraft. The video iOS_Minecraft made looks very realistic—you are hardly able to tell that it’s not Pocket Edition!