As an adjective calcareous
is resembling or containing calcium carbonate or limestone; chalky.
As a noun phytoherm is
(geology|biology) a calcareous 'freshwater reef', generally built up from autochthonous petrification of bryophytes, funghi, algae and cyanobacteria.
phytoherm
English
Noun
(
en noun)
(geology, biology) A calcareous 'freshwater reef', generally built up from autochthonous petrification of bryophytes, funghi, algae and cyanobacteria.
References
*Pedley, H.M. 1990. Classification and environmental models of cool freshwater tufas. Sedimentary Geology 68 , pp. 143-154.