| OOLITE | Any sedimentary rock, especially limestone, consisting of tiny spherical concentric grains within a fine matrix (6) |
| OOLITIC | Type of limestone consisting of tiny spherical concentric grains within a fine matrix |
| CALCITE | A common constituent of sedimentary rocks, especially limestone |
| DIAMOND | An exceptionally hard mineral found in certain igneous rocks, especially the kimberlites of South Africa |
| RING | A band of gold or silver, sometimes set with gems; an "elf circle" of champignon mushrooms on a woodland floor; one of the concentric markings in the trunk of a tree; or, a disc of matter orbiting Sat |
| WHORL | Word for a spindle's flywheel or wharve originally, later a pattern of concentric circles; a single convolution in a spiral shell; a radial arrangement of petals or leaves; or, a gyre or swirl in a fi |
| ATOMICAL | Consisting of tiny bits |
| TUNIC | A concentric layer of an onion; the coat of a sea squirt; a gym slip; or, an ancient Greek or Roman chiton (5) |
| PEA | Tiny, spherical veggie |
| TARGET | A board or butt marked with a series of concentric rings for archery; or, any object aimed at (6) |
| SATURN | Planet whose concentric icy rings are thought to be made up of the remaining pieces of a Titan-sized moon shattered by its gravity (6) |
| COAXIAL | Of a cable, transmitting high-frequency electrical signals by means of two concentric conductors separated by an insulator (7) |
| RINGS | Concentric inner markings of a tree trunk used to identify its age; or, tokens of eternal love (5) |
| ANNULUS | A plane surface bounded by two concentric circles, like a washer |
| LAYER | Any one of Earth's concentric coverings including its mantle and crust (5) |
| GOBSTOPPERS | Large hard sweets consisting of different coloured concentric layers (11) |
| COIL | Shape formed by a series of concentric circles (4) |
| TAMBOUR | Wooden frame made from two concentric hoops for keeping embroidery cloth taut; or, a buttress on a real tennis or Eton fives court (7) |
| ROSETTE | Badge made of concentric loops of ribbon (7) |
| BULLSEYE | Central concentric scoring zone of an archery target (5-3) |
