The effect when you have 3 crystal beast monsters in your m/t zone states that you can negate the activation of a spell or trap. I am wondering, since the card states that you can trib. one crystal beast "monster" , can you trib one in your m/t zone also? Since they become continuous spells and not monsters anymore?

If a "Crystal Beast" is in your s/t zone, it isn't a monster anymore. It is a Continuous Spell Card.

You must send 1 "Crystal Beast" monster you control, so it needs to be a monster in your Monster Card Zone.

That's what I thought but my friend didn't beleive me, thanks for clearing it up.