Gemsbok Cucumber, a source of water

The Gemsbok cucumber is an edible fruit-like plant which can be eaten when it is ripe enough, although it is slightly bitter. It derives its name from the Gemsbok, as it is one of the Gemsbok favourite sources of moisture.

These fruits are also eaten by jackals, squirrels and other creatures of the desert. Nothing in the desert goes to waste. Even the empty shells collect rainwater during the summer rains, which provides yet another source of water for rodents and insects.
Sources:
https://en.wikipedia.org/wiki/Acanthosicyos_naudinianus

Similar References:
Tsamma Melons, a source of water