### ring:

Fairy ring
* Most fairy rings are only present for one to four or five years and eventually die.
* appear as circular green or dead areas that continue to enlarge for several years
  - in any lawn, golf course or other turf areas during spring and summer months
* are actually a result of mushroom growth
  - most severe on light-textured, infertile, droughty soils
  - of little concern in lawns
  - usually most severe in light-textured, low fertility soils low in moisture
* can grow to impressive dimensions
  - occur on any type of lawn
* common disease of Kentucky bluegrass and most other turfgrass species.
* develop over a wide range of fertility levels and soil and climatic conditions.
* develops most frequently in soil high in organic matter such as undecomposed thatch.
* is caused by a number of mushroom fungi that live in the soil and thatch layer
  - the only cause of extra greening at the leading edge of areas
* survive as spores or as dormant mycelium.

Inner ring
* are a part of everyone's lives
  - compositionally similar to arms but have a different origin
  - part of everyday life
* depict the sun, moon, and stars.

Nerve ring
* is located near center of the isthmus.
* surrounds esophagus just behind excretory pore.

Piston ring
* Most piston rings are part of pistons.
* Some piston rings have pressure.

### ring:

Tree ring
* appear as alternating light bands of early wood and dark bands of late wood.
* are an important method of dating in archeology and serve as a record of past climates.
* are another easy example to see how they are also influenced by magnetic flux
  - source of information about the recent and ancient past
  - more visible in places where the seasons change between hot and cold
  - the basis of dendrochronology , which dates wooden objects and associated artifacts
  - used to make radiocarbon dating more accurate
  - wide in a good and narrow in a poor growth year
  - wider during wet years and more narrow during dry years
* can show where a wooden object was made.
* dating is an accurate technique for determining the dates of archaeological sites.
* differ in pattern, width, and density depending on the cllimate conditions of the time.
* grow under the bark, and the bark is pushed out while the tree is growing.
* have many uses.
* indicate tree growth.
* record both the negative and positive effects of volcanic eruptions
* reveal when fires occurred during the tree's life.
* show the years of growth for that particular tree.
* tick out of time with automata driven by tiny cogs and springs.
* vary in width from year to year, depending on temperature and the amount of rainfall
+ Growth ring: Trees
  * Tree rings grow under the bark, and the bark is pushed out while the tree is growing. The inner part of a growth ring is formed early in the growing season, when growth is fast and is known as early wood. The outer portion is the late wood, and is denser than early wood. Many trees in places with hot summers and cold winters make one growth ring a year.
  * Rings happen because of the change in growth speed through winter, spring, summer and fall, so one ring usually marks the passage of one year in the life of the tree. Tree rings are more visible in places where the seasons change between hot and cold. Enough moisture and a long growing season result in a wide ring. A dry year may result in a very narrow ring. Trees from the same area will tend to grow the same pattern of rings. Cut all the way though a tree horizontally, like a stump, to find the growth rings.
  * Tree growth rings can tell us about the ancient climate and growth rings can be used to tell the age of a tree. Growth rings can also be used to date the wood in old buildings, ships and frames for paintings. Tree rings are used to make radiocarbon dating more accurate.