This cave system marks the first appearance of zombie-type monsters. Cecil's Dark Sword will inflict only 1 damage to these (or slightly more on a critical hit), making it essentially useless. His Darkness command, if available, doesn't work very well either, having just a quarter of its usual effectiveness against any undead monster, which at least outdoes the paltry single point of damage from his regular attack.

Cecil doesn't struggle as much against zombies in the DS remake, since they merely halve damage from his sword instead of essentially negating it.

Not far into the cave, an old man blocks the way forward. If Cecil hasn't seen Rosa yet, the old man will rather rudely refuse to get out of the way.

However, after Cecil has found Rosa, the old man shows a little more patience.

Tella isn't nearly as frail as Rydia, being level 20 and likely having more hit points than Cecil for now. That doesn't make him a fighter, though, and he should normally stay in the back row for his protection. On the other hand, he's quite powerful for this point in the game, having all the basic offensive spells plus a number of other useful ones, including Aspir, Blink, Esuna, and especially Cura, which makes him an outstanding healer for the time being.

Unfortunately, Tella has very slow stat growth. His max HP only goes up 24~27 each level, and while his max MP of 90 may seem like a lot for now considering Rydia started with only 10, it's actually low for his level (most casters have well over 100 by level 20) and additionally never increases. His strength and stamina actually decrease from their already unimpressive initial values of 5 and 7, dropping to 1 by level 30, and his intelligence and spirit don't increase at all either until level 43. Rydia will match him on offense when casting the same spells once she hits level 12, then pass him at 17.

The original JP version also gives Tella the Remember command, which lets him attempt to cast a more powerful spell. Unfortunately, it's random, and more often than not casts only a basic spell, or even fails outright. Still, it's an interesting bit of characterization, hinting at how powerful he must have been in his prime. The NA and ET versions lose this by removing the command, presumably for simplicity's sake.

In the DS remake, his level and HP aren't quite so remarkable, and though his MP is still stuck at 90, he has unusually high magic stats for this point in the game. Even better, player stats affect weapon-cast spells in this version, so he can obliterate common monsters just by using a Rod as an item.

In any case, check behind the nearby waterfall for some goodies before going deeper into the cave...

After passing through more of the cave, the party comes across a room with a strange formation and a symbol on the floor.

They set up camp, and Rydia soon falls asleep.

Tella looks upset.

Morning comes, and the party sets off again.

Don't miss the Ice Rod shortly ahead, which works well against most reptiles and similar creatures. Cecil will get a stronger sword near the exit as well.

"It" being the monster.

The EasyType changes テントでも　はる (TENTO de mo haru, put up a Tent or the like) to やすんでおく (yasunde oku, rest in preparation), oddly making the suggestion more vague and less directly helpful.

As promised, the exit leads to the surface, with a small open area before another cave. This is a good time to heal and save.

The cave leads to the top of a large waterfall.

And this being that sort of game, jumping isn't suicidal and doesn't even hurt. Cecil will get some new armor, and then it's boss time... I hope you like tentacles.

Cecil should keep attacking, as usual. Rydia does the most damage with the Chocobo summon, though Thunder isn't bad either. Tella should cast Thunder for damage, or go the defensive route and cast Blink on allies as needed to avoid taking damage.

Octomammoth pointlessly absorbs Holy, but is conveniently weak against Dark as well as Thunder. After taking damage three times, and every other time after that, its speed drops slightly and its graphic loses an arm, until it reaches its minimum speed with a single arm.

When Octomammoth is down to two arms...

If you've made it this far, finishing it off should be easy, particularly since Octomammoth only ever uses normal attacks.

In the DS remake, Octomammoth seems to hit harder when weakened. Chocobo doesn't work as well, either, since spell power was rebalanced. Rydia seems to work better as a healer, while Tella's much improved magic stats make him significantly better at inflicting damage.

And so they leave the cave behind. Unfortunately, no sooner does Damcyan Castle come into sight but the Red Wings fly past and bomb it...