1. Place down a glass block. I was using Light Grey Stained Glass)

2. Place a quartz slab on top of that block. (lower-half slab)

3. Surround the slab with any blocks. (tried Grass and Lt. Grey Glass, and double quartz slab)

4. Waterlog the slab.

VIOLA! You have the mossy brick texture on the water!

You can also place the lower slab into the water and get the same effect.

(The slab/water combo section is also visually glitchy as you move around.)

Once the water starts flowing, the texture reverts to the normal water texture.

Quartz slab on grass = normal water texture

It only seems to happen when the slab is on top of glass. (with one exception so far)

In attachment IMG_6171.jpeg: Left side, top row, is slabs on top of one glass block, and one grass block. For some reason, the mossy brick texture is active on both. When I tried to recreate the same setup (bottom row left side) it only occurred on the slab over glass.

I have no idea why the discrepancy.