Why There is Crack in KAABA WALL??

[Ibn_Sadique]

@zer01

http://www.hajjguide.org/holy_kaaba_13th_rajab.html ← some pictures.

Quotation from the link ^

"We realize that:

1. The crack opens every year (The night the Imam was born) even though they try concealing it.2) The crack still opens even after the Ka’aba was demolished by Bani Ummaya (la).
2. There is a scent that comes out of the crack that does not exist in any other part of the Ka’aba.
3. In our narrations it is mentioned that the Prophet (saww) touches the Rukn al Yamani.

I wonder which heavenly scent and light emanates from the Place where the best of Mankind and Creation (RasoolAllah (peace be upon him)) pace was born.

Anything from Shia sources??