Check out a very robust S. gigantea from this link. http://www.centraltexasgardener.org/2017/11/giving-thanks-for-nature/

Appreciate the feedback Crystal! Check out another genus, the Stapelia. Again without flower, this is only a suggestion. Click on images to enlarge for one species in the group, the S. gigantea from the included link below. Best wishes! http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=276899&isprofile=0&

It’s never had a flower in 3 years. And it’s slick, no thorns. Just small nubs. And grows so fast it hangs all the way down the baker’s rack in porch. Also I can root a piece when they break off just sticking it into dirt somewhat like a lifesaver flower or plant.

Flower images a species in the moonlight cactus, the Selenicereus pteranthus. http://www.florida.plantatlas.usf.edu/Photo.aspx?id=13094

It’s hard to tell for certain with out flowers. For now, I’m guessing maybe either a species in the moonlight cactus (Selenicereus) or the dragon fruit genus (Hylocereus). Checkout the included link for information on the Selenicereus genus. Flowers are needed for a confirm ID. When it blooms and you still don’t know, make new post with photo of flowers. Best wishes! https://en.wikipedia.org/wiki/Moonlight_cactus