Dear Rabbi,

The Sefer Ta'amei Haminhagim states in the name of Eliyahu Rabba and Zohar that there is a bone in the brain which never vanishes. You can't burn it, break it or mill it. I believe it b'emuna shelemah - with utmost faith - but I would like to know if someone could tell me more about it: Did you see it or read about it or hear a Rav ... or a physician who could give the name of such a bone? Thanks to you.

Dear Dr. Aharon Altabe,

Yes, according to tradition there is a kind of bone or organ no bigger than a barley corn called the luz or neskvi; its shape is almost cubic and apparently it lies at the top of the spine, inside the skull underneath the brain. It is described as having within it many intertwined spider-like blood vessels.

It has curious properties: It receives nourishment only from food eaten Saturday night at the melave malka meal. And, yes, it is indestructible and doesn't decay in the grave. The Midrash says that the Roman Hadrian once took a luz and tried to grind it, burn it, and dissolve it in water, to no avail. When he hammered it against an anvil, the hammer and anvil broke!

The future resurrection of the dead will be from this bone; that is, a person will be resurrected from his luz bone.

The idea behind it is this: The luz symbolizes the point where physical and spiritual meet. Thus, it is nourished only from melave malka, the meal eaten between the spiritual Shabbat and the physical weekday. It's like the Western Wall: Just as the Western Wall will never be destroyed, and from it the Third Temple will be built, so too the luz is never destroyed, and from it the person will be re-built during the future resurrection.

Regarding the precise identity of the bone, I advise asking Dr. Eli Temstet from Paris. I am sure he can be of help.

Sources

• Sefer Ta'amei Haminhagim 425
• Bereishet Rabba 25
• Mishna Berurah 300:2