Elephant's Foot

Etymology
, in reference to its bulky mass and wrinkled appearance which resembles the foot of an elephant.

Proper noun

 * 1) A large mass of corium beneath the remains of Reactor No. 4 of the, which was produced by its meltdown during the  of 1986.

Translations

 * Russian: Слоно́вья нога́
 * Ukrainian: Слоно́ва нога́