Texas, maybe coral?

[yearsago]

south of Austin Texas, halfway up a small mountain, dug from a pit in the ground

the one circled in red I'm pretty sure is just sandstone, but i thought I'd check. The other one im curious about.
The camera didn't capture it well but its embedded on crystal stone, opaque, yellowish. I've found one before with the same pattern but i lost it. is it a type of coral? I found a different type of coral in the same spot before.

[JohnJ]

More photos of each could help.

[yearsago]

sure