Board Thread:Theories and Speculation/@comment-27821571-20160915183730/@comment-734582-20160918080240

Seelentau wrote: But that's just my headcanon. To be honest, i thought a similar thing: it's the seal that binds his body (although i hadn't thought of magnet release). He needs it because he uses his body in jutsu, unlike Matatabi who only spits some blue flame. (Ie Shukaku transforms his hands into a giant sand pyramid).

In the manga the rasengan chakra becomes brown though, so i think that's the Magnet release part (since, unlike e.g. Lava, magnetism isn't really visible) rather than just adding curse seals.

It seems that Desert Layered Imperial Funeral Seal isn't marked as Magnet Release though, not sure if there's anything in the databooks or whatever to suggest that Shukaku's markings are magnet release (ie in a jutsu he uses).

All in all, it seems to me that Shukaku is simply a beast with sand control because that's his body and Curse marks to give him form. It's not like Son Goku has lava to keep it's body warm or Kokuo steam to move. If Magnet Release were involved in his body, he'd use other materials as well (e.g. iron as a skin).