"A squat reptile with a massive shell, the tortoise glares at you fearlessly."
Can be quite hard to kill for most early game characters due to their decent Armor Value and good chunk of Hit Points. But later on they will be more of an annoyance for most characters.
Legendary versions of irritable tortoise always spawn with some great saltbacks along with other irritable tortoises, which will all be agressive torwards the player character. Unless you have managed to raise up reputation torwards them enough to make them not be hostile torwards you, which can be hard because irritable tortoises have their base demeanor set on aggressive, unlike great saltbacks.