See below to lengthy for answer body but this has a pretty fair take on it. (IMO)

Shell rot is pretty common, there is a lengthy list of suggested home remedies. See info below-

The verb of length is lengthen.
Others, depending on the tense, are lengthens, lengthening and lengthened.

Some example sentences are:
"We will lengthen the road".
"She lengthens her hair".
"We are lengthening the deadline".
"The ghostly arm lengthened towards the grave".

The process of mitosis. It's a pretty lengthy explanation, so check out the link below for the explanation.

Pretty much- they have the same basic information, but some are more lengthy if increased hazards/safeguards required.