If u see this do not approach they have over 10,000 mele damage and is the fastest creature on the island if u encounter it on accident it will slaughter u and your mount so be wary and stay alert I u somehow manage to tame it you will be the alpha of your server.
Achatina's are by far the hardest animals to escape on the island. Their insane movement speed is devastating to you and your dinos. These snails are also very powerful and will kill your gigas within, at least, 24 hours! The best thing to do when you see them is bola them and run.