Yes, POLYZOANS is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, L 1, Y 4, Z 10, O 1, A 1, N 1, S 1.

Is it a valid word?

POLYZOANS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

sessile aquatic animal forming mossy colonies of small polyps each having a curved or circular ridge bearing tentacles; attach to stones or seaweed and reproduce by budding

Also: sea mat, sea moss, moss animal.