The Giant snail (Achatina Acidia Giganteus) is a large snail that can be encountered during the Temple Trekkingactivity. It uses an incredibly accurate and hard-hitting magical ranged attack, which almost never misses, even against ranged armour. It is not uncommon for a level 146 snail to hit near or over 200. Wearing a snelm will sharply reduce the amount of damage taken, but this does not affect the accuracy of the snail's attack. Protect from/Deflect Missiles will block the attack completely, and is preferable to using a snelm if multiple snails are attacking (as is often the case).
Giant snails have fairly high Constitution and Defence, so boosts are advised when fighting. When under attack, they will spend most of the fight trying to retreat, until they are backed up against something. These monsters will shift their aggression to the player if they are attacked while engaging the player's escort. However, if the escort is fighting a snail and the player stops attacking that snail, it will shift its aggression back towards the escort until the player begins attacking it again.