Concentric objects
Videos
In geometry, two or more objects are said to be concentric when they share the same center. Any pair of objects with well-defined centers can be concentric, including circles, spheres, regular polygon
Ripples in water
Histology of a Pacinian corpuscle, in a typical expanding circular pattern.
Tree rings, as can be used for tree-ring dating
Whorl
Videos
A whorl is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects.
Concentric objects
…line through the center), spheres, cylinders, conic sections, and surfaces of revolution. Concentric objects are often part of the broad category of whorled patterns, which also includes spirals (a curve which emanates from a point, moving farther away as it revolves around the point). In the Euclidean…
Botanical whorls: sepals, petals, leaves, or branches radiating from a single point (photo of flower of Friesodielsia desmoides, family Annonaceae, juxtaposed with diagram of axial cross-section)
Mollusc whorls: Each complete 360° turn in the spiral growth of the shell of the mollusc Anisus septemgyratus, family Planorbidae.
A hair whorl is a patch of hair growing in a circular direction around a visible center point.
In a fingerprint, a whorl is each ridge arranged circularly around a central point on the finger.