Cactolith

A cactolith is "a quasihorizontal chonolith composed of anastomosing ductoliths whose distal ends curl like a harpolith, thin like a sphenolith, or bulge discordantly like an akmolith or ethmolith."
The term was coined by Charles B. Hunt, a USGS researcher, in his paper "Geology and geography of the Henry Mountains region, Utah" (1953). He was in fact describing an actual geological feature—a laccolith which he saw as resembling a cactus—he was also, tongue-in-cheek, commenting on what he saw as an absurd number of "-lith" words in the field of geology.