Montmorillonite is chemically made up of hydrated sodium, calcium, aluminium, magnesium, silicate hydroxide. Sometimes Potassium, iron, and other cations are common substitutes, the exact ratio of cations varies with the source the Montmorillonite is from.
Montmorillonite or Bentonite are clays, and like most clays is great at absorbing minerals. Their absorption capacity is as much as 8 times greater than other clays.
Montmorillonite is effective as an adsorptive of heavy metals.
So while Montmorillonite or Bentonite are made up of a lot of good stuff that shrimps or fish might need in their bodies, the minerals are locked away in the clay. How much of these minerals are released is the question no one has determined yet.
How Montmorillonite or Bentonite is beneficial to the shrimp hobby is not it's mineral make up, but it's ability to absorb heavy metals and contaminants.
HOWEVER, since its got great abilities as an absorbent, what it's already absorbed (contaminant or otherwise) will be added to the tank unless you can be certain it's pure Montmorillonite or Bentonite.
In conclusion, If it's primary benefit is it's absorptive capabilities and not release of those minerals, isn't cheaper alternatives like activated carbon or Purigen, Macropore better ?
I'll leave that question for you to ponder.
You bet dude.
Did you know that apart from Phosphorus and Calcium, Potassium is the 3rd most abundant mineral element in the body (human, animal, fish or shrimp)?