[Phil V.]

"concretions" . . . as in requiring a liquid environment to form? Past liquid environment is where my thoughts track.

[Aracelis]

"concretions" . . . as in requiring a liquid environment to form? Past liquid environment is where my thoughts track.

Yes, it would require an aqueous environment according to the geology that we are familiar with (Earth). Here's a good link to a page describing concretions:

Concretions, Thunder Eggs and Geodes