e/Microatoll

Information
has gloss	eng: A microatoll is a discoid colony of coral, dead on the top but living around the perimeter. Growth is mainly lateral, as upward growth is limited by aerial exposure, and microatolls may be up to 1 m in height and 6 m in diameter. They are named from their resemblance to island atolls formed during the subsidence of volcanic islands, as originally suggested by Darwin (1842). They act as natural recorders of sea level, which allows the monitoring of sea level changes on coral atolls thought to be susceptible to the effects of sea level rises in response to global warming. They have also been used to quantify and date changes in relative sea level in seismically active areas, and to provide information on changes in sea surface temperature using oxygen isotope values as a proxy. Microatolls are formed by several species of the genus Porites, but examples have also been described from Acropora, Heliopora, Favia, Favites, Platygyra, Cyphastrea and Goniastrea.
lexicalization	eng: microatoll
instance of	(noun) a reef consisting of coral consolidated into limestone coral reef