What are the two main functions of sclereids or stone cells and are sclereids alive at maturity?

Explanation:

A sclereid is a type of sclerenchyma (a plant cell type characterized by having a thick and lignified cell wall) of varying shapes that are typically shorter, with an extremely thick cell wall and whose function is to provide strength and support primarily. Sclereids are also responsible for the gritty texture of pears and guavas.

They are non-living at maturity as they don't require further maintenance, but they maintain the structure.

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