rplatham edit: this also affects normal texture. See screenshot in MCPE-16853.

I don't know if it's a Plastic Texture pack bug (pretty sure it is because I haven't seen any reports) but anyways when I placed down a Prismarine block, it looked like it had differnet textures of it, but squeezed into small parts, example: from the left (or the right, depends on where you're facing) would be a purple-ish, 2nd would be normal 3rd etc. So the real one was: from the left (or right if you look at it from a different side) was the normal texture, 2nd was a Prismarine texture with a color line formed in kinda like a Mossy Cobblestone vine texture (forgot which color the line was, pretty sure purple-ish, my tablet battery died, so I forgot) 3rd was the exact same, but with a different color (pretty sure it's green, again my battery died) and 4th, (I don't think there is a 5th one) was the exact same with 2 and 3, but with a blue-ish color (again my battery died, so I'm trying to remember it). You can reproduce by having the Plastic Texture pack on, then place down the Prismarine block. Now you'll see the bug. If you can't see this, then it might be my Samsung Tab 3 Lite. There is no Samsung Tab 3 Lite on the device list (I'm pretty sure).