When tamed, the Achatina can produce Achatina paste, an alternative to cementing paste, passively when on wandering. You could also collect it when they are moving, their paste/slime will be on the ground shaped in a similar feces ball.
The Achatina is a massive snail, mostly used for its production of Cementing Paste, or as a pet. This creature produces its paste passively — and quite frequently — so many survivors keep them around their bases. However, its usefulness pretty much ends there, as it cannot attack and moves quite slow. The Achatina must be tamed violently.