It looks like Syngonium podophyllum. It's tropical so it prefers a moist (not wet) spot and can take more shade.

Pachyphytum sp.

Yes, usually rot. You can just feel it and the color is very much telling too...but if unsure, take a branch and start cutting thinner slices from the bottom to see what the flesh looks like. If very soft, you may not be able to get clean cut. Use a blade, scissors or pruning shears will just squish it. If you find firm flesh, there is a chance that it could be rooted - few of the stems may have some viable parts. The longer, thicker stem on left seems to have yellow tip too -BUT very light color could be caused by plant being shaded too much for a while. I am assuming rot since the main stem was rotted, and being able to see only photos.

I know it's a little late, but evidently, a lot of May posts didn't get any replies. Those look like army worms from what I can see.