Opalized wood!

This rock looks like opalized wood or opalized petrified wood.
Here's why:
* Wood Grain Texture: You can see the distinct grain and texture of wood, indicating it was once a piece of a tree or branch.
* Opal-like Sheen/Color: The light blue, almost milky appearance with hints of other colors (like the brown you see in the center) is characteristic of opal. Opal is a mineraloid that often replaces organic materials, including wood.
* Fracturing: The way the surface is cracked or shows a "crazed" pattern is also common in opal, as it can be somewhat brittle.
Opalized wood forms when silica-rich solutions infiltrate wood and replace the organic material with opal, preserving the wood's form. The presence of opal gives it a unique look compared to other types of petrified wood.