The third plant is an epiphyte. I believe it is Rhipsalis
. It may be the species monacantha
, but I'm not sure of that, and I have no
idea of the variety. There are many hybrids of Rhipsalis
The stems are supposed to hang down as yours are doing, but they are not supposed to be wrinkled. The epiphytes grow on trees in the jungle. They are succulents, but are not desert cacti, so they need more water. If I were you, I would move it to its own container, because it will want more water than the Echeveria and the Aloe. Since it is a jungle plant, it won't do well with as much light as the Echeveria and Aloe will need, either. It will do best in its own container, where its needs can be properly met.
I like to water my plants by immersing the entire pot in water deep enough just to cover the rim. I leave them there until I no longer see air bubbles breaking the surface of the soil. Then I remove them from the water and place them in the sink, allowing them to drain for about an hour or so. This method ensures that the entire root ball gets moistened. If the soil feels dry, and the pot feels lightweight for its size, then it's time to water again. If the skin of the plant becomes slightly wrinkled, it is past due time to water the plant, but likely no great harm will have been done. I certainly wouldn't allow it to happen as a matter of routine, however.