According to Hindu scripture, the Tulsi plant was a woman named “Vrinda” (Brinda; a synonym of Tulsi). She was married to the Asura king Jalandhar, who due to her piety and devotion to Vishnu, became invincible. … Vrinda cursed Lord Vishnu to become Shaligram and to be separated from his wife, Lakshmi.

Shaligram is a blackstone brought from Gandaki river in Nepal. It is most revered stone worshipped by Vishnu Bhakts.

According to Shastras, keeping Shaligram ji along with Tulsi benefits the family in 6 dimensions: Noble way of life, Wealth, Protection from evil, good health, worldly pleasures and blessing from Lord Vishnu

Mainly Shaligram is worshipped by offering panchamrit snan ,Pure water,Tulasi water daily.
Shaligram stone is considered a form of Lord Vishnu.

Never keep this on floor, even on a cloth. If at all you have to keep them down, place them on a wooden surface that is clean.

It should be worshiped with, by daily Tirumanjana ( abhisheka) by water drawn from pure sources, dried with a pure cotton cloth, with a dot of sandal paste over it, and placing a TuLsi leaf and a flower on top of it.
it should be worshiped chanting ashtAkshara manTra ( Om namo nArAyaNAya) and Dwayam (Sriman nArAyaNa charanau SaraNam prapaDyE, SrImaTE nArAyaNAya Nama:) duly received from your AchArya or your father/grandfather.

You should announce (nivedana), with any good fruit, that you owe your existence with food you got due to His System.

Most of the shaligrams you see are just egg shaped stones. It is extremely rare to find original shaligram.
Today, any piece of stone is sold as shaligram . It’s one in a billion kind of a stone. If you happen to pick a real shaligram , it can make your life heaven if you know how to use it .
Its not a joke or child’s play to keep Salagrama at home, it runs in the family, and there has to be devotion and a lot of practice of rituals to be followed, Its like Lord Vishnu is present physically.
People living a simple life shouldn’t keep one and Manging the energy of shaligram isn’t for everyone. Shaligram is like a mini cosmos . It carries same type of energy as the universe.
Its energy can create disasters if kept the wrong way .