That is a leaf (not stalk) and IMO, the plant rotted. It was most likely overwatered. One week of not watering is not a problem for majority of succulents in typical conditions so I don't believe that was the problem.

It is potted in a container that doesn't seem to have drainage hole (does it?) - and that, together with watering so often, is almost guarantee of death.

Ok, thank you. I have amended the language. That is helpful in making sure I don't become paranoid and over-water the other succulents. Still looking for an ID though. I don't think it has a drainage hole (I was surprised when I saw this also) but the other succulents are in similar planters and they seem to be doing fine. I think she kept this plant for a while in this pot, so I'm not sure why the pot should make a difference (other than the overwatering part.)

Even so, any ID ideas?

Not sure about ID.

There is Aloe variegata that has very similar looking leaves - but it grows very upright and has thick trunk from which leaves grow. It could be one of the gasteraloes too.

Are there any 'teeth' on the leaf margin? Maybe you could get a clear, sharp photo from different angle.

Here is photo of very young Aloe variegata, so you can see it's growth pattern and the spots on leaves. There are no teeth on the margin:

Other plants in same kind of containers may look fine, since it doesn't happen over night. Your boss may be watering 'in sips' in order not to overwater, but that kind of watering is not best for the plants in the long run. If watered 'just a little', it takes time for excess water build up, but it eventually does and plant ends up sitting in the muck at the bottom. That is what kills roots.

It may help you to use a bamboo skewer (or a chopstick - skinnier is better IMO). Insert it all the way into potting soil, avoiding the roots. When taken out (couple of min is plenty), it will be either dry - that means watering time. If it comes up with tiny particles sticking to it, and it feels cold/damp when touched to top of your hand or cheek, do not water - there is still plenty of moisture. There is saying about watering succulents: if in doubt - don't (water).

Under-watering is sometimes a problem too, but in general succulents will recover easier from being dry than too wet.

Could be a Gasteraloe. I have one that looks like OP's pic, but much smaller and more brownish from sun exposure. The Gasteraloe is just a guess though, because I haven't yet got a positive ID on mine.

Let's see if I have a picture.. This was around a month ago or more, newly acquired. The leaves were thin back then, now they are a bit more plump.

Wow, you guys are amazing. Yes, it has INCREDIBLY minuscule teeth. After looking at further pictures, the Gasteraloe's leaves look a little too wide, but it wasn't growing upward in quite the way the Aloe variegata seems to be. This looks exactly like it and claims to be Aloe variegata but holy smokes batman, it's expensive!! Out of curiosity, how long would it take for the root rot to take hold? Wondering if I was the root (pun intended) of the problem... Also, thanks for the bamboo/chopstick tip - very helpful!

I am not sure if there is a way to tell how long it will take for plant to rot; I mentioned few possibilities in previous post.

BTW, that price seems to me out of line. It does look well grown, but...Even in Canada, where we pay more for everything :( I would pay around CD 6-8 $ for a plant of similar size. This is what you pay for all that extra $$$ - cellophane and tissue paper and the ribbon...doesn't even mention if the container is included (better not - it's likely drain hole-less, lol):

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