For ten points, name this type of ritual bath, used for purification in Judaism.
This object is discussed in the sixth tractate of the Tohorot in the Mishnah, which states that to be valid, one of these objects must contain at least 40 se'ah. A dispute exists over whether a person with uncombed hair or dreadlocks can properly use this object, and this object is used during the second stage of taharah, the preparation of bodies for burial. Keri, Zavah, and Niddah are states caused by discharge of bodily fluids that this object can remove via tevilah, or ablution via full-body immersion. For ten points, name this type of ritual bath, used for purification in Judaism.
This object is discussed in the sixth tractate of the Tohorot in the Mishnah, which states that to be valid, one of these objects must contain at least 40 se'ah.
{Mikvah}