cystolith
noun
cys·to·lith ˈsi-stə-ˌlith 
: a calcium carbonate concretion arising from the cellulose wall of cells of higher plants
Word History
Etymology
German Zystolith, from zyst- cyst- + -lith
First Known Use
1857, in the meaning defined above
Medical Definition
cystolith
noun
cys·to·lith ˈsis-tə-ˌlith
: a urinary calculus