Publisher's blurb: The Cavern Wall group of Naked Geomorphs contains 22 tiles, each with two or more unjoined multi-position openings (CD, CSD, CSSD, etc.) and the remaining positions filled with rock (R). Some tiles have three multi-position openings, two of which are joined into a passage. Sets A and B are completely interchangeable. I.e., tile C35A can be replaced with tile C35B, without changing the basic structure of your map. Set A has more complex outlines than Set B, with narrow protrusions and indentations.