TIPP: Achatinas can produce organic Polymer. You can just craft a fridge with the organic Polymer and destroy it. Every time you destroy a fridge you get normal Polymer back. That means you can transform organic Polymer to normal Polymer. I found it out yesterday by myself.
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.