I know the measurement of mg, but what oh what is mcg

I figured I would crush the tablets & feed them in powdered form.
Here's what the bottle says:
Serving size, 1 tablet, 1 tablet = 150 mcg. 100% Iodine from kelp.
Other ingredients: cellulose, magnesium Stearate (vegetable source), stearic acid (vegetable source), vegetable coating.
Contains NO sugar, salt, yeast, wheat, gluten, corn, soy, milk, egg, shellfish or preservatives.
Also says" Kelp is a large, leafy brown algae that belongs to the seaweed family & grows in the colder waters of the world's oceans. It is a good source of marine minerals, including potassium, magnesium, calcium & iron, & an excellent source of iodine. As with most green foods, kelp also contains vitamins & cell salts."
I wonder if I should offer the ground kelp in finger cups
