No, they're not monsters anymore. When they're played to your Spell and Trap Card Zone, Crystal Beasts become Continuous Spell Cards, and thus cannot attack, defend your Life Points, be Tributed, become equipped to "Relinquished", be stolen by "Change of Heart" or destroyed by the effect of a card like "Raigeki" or "Tribute to the Doomed". They CAN be destroyed by "Mystical Space Typhoon", "Heavy Storm" or "De-Spell", because they're now Continuous Spell Cards. They also can't use their effects when they're crystals. They can be tirbute for ra of thunder.