Vining Caudex Plant - Mystery ID - Awesome Huge Caudex

NOBODY has been able to identify this plant - and I've run it by all the experts I can think of. It's something special. Maybe you can ID it! It forms a huge caudex like the first photo (mother plants). The vines will root from cuttings, and form a caudex as well. Very succulent leaves, and VERY drought/heat tolerant. I'm not sure what would upset this plant! Second photo is the plant being offered, shown in an 8" bowl.    Dormancy: This plant is winter and drought deciduous. If you purchase this plant in the late fall/winter/early spring, it will not have leaves. As it starts to warm up, you can water more frequently to encourage it to start growing new leaves.  Even during spring/summer/early fall, this plant may still drop leaves in transit. This is normal and expected. When plants are put in a stressful situation, which includes being bare rooted and put in a dark box for a few days, it is going to conserve as much energy as it can. It does this by dropping its leaves. Once it arri