Yes, TESTUDO is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, S 1, T 1, U 1, D 2, O 1.

Is it a valid word?

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

a movable protective covering that provided protection from above; used by Roman troops when approaching the walls of a besieged fortification
type genus of the Testudinidae

Also: genus testudo.