Judging from the number of new stems splitting from the same spot in the 2nd pic, I'm leaning toward Rhipsalis.
Determining which of the suggested names belong to this plant is fairly important in this case, for both sun & moisture preferences. Rhipsalis plants are epiphytes (growth pattern similar to orchids) from moist, rainforest jungle climates. Euphorbia tirucalli is a terrestrial full sun plant from hot, dry climates.
Both could easily rot at the roots in a dense, airless soil.
