It is a Stapeliad type of succulent. You may have to wait for it to flower and post a picture to ID it further. It also needs bright light, yours is green, indicating lower light levels than would be ideal. Still looks fine but it may not flower as well in lower light conditions. HTH.

There is a pic of one species below, showing some of the stalks and a flower.

Here is a link that might be useful: {{gwi:474520}}

Wow, I was totally off on that one. Thank you, Steve! The light might explain why some of the stalks have started getting droopy.