Yes, CHITON is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, I 1, T 1, O 1, N 1.

Is it a valid word?

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

a woolen tunic worn by men and women in ancient Greece
primitive elongated bilaterally symmetrical marine mollusk having a mantle covered with eight calcareous plates

Also: coat-of-mail shell, sea cradle.

Not playable in Scrabble US: POLYPLACOPHORE.