cone-in-cone

from The Century Dictionary.

• In geology, appearing to be made up of cones closely packed one within another, as some limestones and marly strata, and very rarely beds of coal.
• noun A fossil of the genus Conularia.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Geol.) Consisting of a series of parallel cones, each made up of many concentric cones closely packed together; -- said of a kind of structure sometimes observed in sedimentary rocks.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective geology Consisting of a series of parallel cones, each made up of many concentric cones closely packed together; said of a kind of structure sometimes observed in sedimentary rocks.