My cat loves spirulina. My spirulina comes in little candy like triangular tablets. Whenever I take my daily dose, she's there waiting for her share.
She is an indoor outdoor cat and I feel confident that her regular consumption of it (just one tiny tablet a day) is keeping her healthy.
The first time I gave my cat spirulina he gobbled it up and then sat there with his eyes bugged out looking around like he just took his first hit of acid and was seeing the world for the first time.
Dosing: 1/2 teaspoon of powder in a pile on the linoleum kitchen floor
Now I mix a dash in his wet food when he looks like he needs some excitement.
He also loves brewer's yeast and the diatomaceous earth (+ - 1/4 tsp/day) seems to be reducing the cyst in his ear. I'll get back to you about that if it goes away entirely.