Yes, CHOANOCYTES is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, O 1, A 1, N 1, O 1, C 3, Y 4, T 1, E 1, S 1.

Is it a valid word?

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

any of the flagellated cells in sponges having a collar of cytoplasm around the flagellum; they maintain a flow of water through the body

Also: collar cell.