An element is involved in the formation of mitotic spindle

An element is involved in the formation of mitotic spindle. Which part of the plant do you expect it to be present? Name the element. Where else can it also be present?

(i) It will be found in the meristems (meristems are the regions in plants, where cell divisions occur for plant growth).
(ii) The element is calcium.
(iii) It is also present in the middle lamellae of cells.