Two textures for underwater sand

Are you sure that isn't clay? I'm unable to replicate this so far, mind sharing a seed?

Seed does not matter, there is a massive lighting bug there, try force relight by placing/destroying blocks

The reason I am asking for a seed is because currently I'm spawning a sand flat world with water on top, and none of those sand are having any lighting glitches. Since lighting glitches are caused by surrounding blocks, it's much easier to replicate if we have a sample world to test with.

It's definitely sand, not clay. And placing/destroying blocks does not help, unless you destroy and replace all the individual sand blocks (which I'm not going to do). Seed is not showing up, maybe I'm looking in the wrong place?

Use the /seed command to find your seed. Or better yet, upload the world in a zip file somewhere and link us to it.

I'm not getting this. Can you re-create your world and try again?

Suspect corrupted worldsave as I'm seeing no land mass around at those coordinates on that seed.

Tried the seed again, but the world was not the same. It looked like the initial chunk was similar, but then there was jungle chunks, ice, and pine trees around it, which doesn't exist in my world. If it helps at all, I created this world probably back in Beta 1.5.

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

I have since deleted the world. As I am unaware that no one else has experienced this bug, I would say it would be ok to mark it as resolved. My best guess is that those blocks were experiencing a lighting glitch.