(n.) A pebble; a stone; also, a heap of stones or rocky debris.

aa abyssal rock alluvion alluvium basalt bedrock block lava brash breccia conglomerate crag debris deposit detritus diluvium drift druid stone festooned pahoehoe gneiss granite igneous rock lava limestone living rock loess magma mantlerock metamorphic rock monolith moraine pahoehoe pillow lava porphyry pudding stone regolith rock ropy lava rubble rubblestone sandstone sarsen schist scoria sediment sedimentary rock shelly pahoehoe silt sinter stone talus tufa tuff