A Quick Note: I won't referred to Mammu as a Monster, but as a Beast - while in my past bios I had often used that latter descriptor deliberately over the former, here Mammu does not fall under the Monster descriptor as 1) he is an Actual Animal, who just happened to be far larger for the size of his species, with the creature showing no special powers, and 2)He is a extinct animal brought back with a Resurrection Spell, where as all monsters (kaiju) are either created by Science (intentional or accidental) or are Alien or Inter-dimensional in origin.

Mammu was the 43rd Beast of the Week in order of Appearance in the Kotetsu Jeeg Anime. The well preserve carcass of a massive Giant Woolly Mammoth, was resurrected by Amaso's Magic and was the only non Phantom/Robot Beast Jeeg confronted, thus not making it a monster. Outside of his enormous size for its species, Trunk, large tusks and Brute force, Mammu did not have any further extraordinary Powers, the fire power literally been brought by the Boy's magically enhance Incendiary explosive Arrows. He was loyal to the child though, and he in return as well, a fact shown by their shared memories in their adventurous past life.

Also, Mammu is the only Beast in the show to not have his title card appear on screen, as tradition of Go Nagai Monsters when they first appear on scene, and if I'm not mistaken (Like Don and Pancho and the MechaDons) these were characters exclusive to the anime. Don't recall seeing them in the Manga.

As Flora is been punished in the Fire Pit for her last failure, Dragon orders Amaso and Ikima to launch their next attack.

In this “WTF, this is the Plan?” they proceed to massacre an entire Paleontologist team, who had just discovered the Skeletal remains of a Cave Boy, close to where a well preserve Mammoth Carcass was found and taken to the Musuem sometime before. Amaso proceeds to resurrect the Boy and as added Bonus, enhance his Arrows with Incendiary Explosive, torching and blasting his way through the Country Side on his way to the city, looking for his Mammoth friend (Mammu, as named by the Boy). Build Base sends Big Shooter to deal with the Massive Fire in the woods, while Hiroshi, Mayumi and Chibi go to the Museum to see the Mammoth in display.

Arriving in the city, the Boy causes further chaos, believing he is still in his time; viewing Buildings as Hills and Mountains, Vehicles as Monsters, and People as other Caveman. Running from the people, he leaps to a tall building and proceeds to fire to everything in sight, causing cars and buildings to explode while calling for his old friend.

At the Museum, Amaso revives the Mammoth, who runs out on a rampage searching for his lost friend the Boy – Hiroshi follows it, with the Beast destroying everything in its path; eventually Mammu joyfully finds the Boy and back together again as a team, they proceed to (as they say in the Hood) further tear the living shit out of the city with the Mammoth's strength and the Boy's enhance arrows. They stumble upon Hiroshi who transforms into his Cyborg Form and fends of their attacks, when MechaDon2 arrives to help, Hiroshi tells Don to entrap the Beast, making a cage with Concrete Pillars.

Elsewhere, Michi finds the Orochi Fortress – Hiroshi is inform and heads to her location while MechaDon2 keeps the Beast and boy trap, avoiding the child's arrows; Arriving on the site of Orochi, Hiroshi transforms into Jeeg but its leg is damage in the fight and the Pantheroid Module is launch at him, connecting. Pantheroid-Jeeg then proceeds to fight the Fortress; In the meantime, Mammu and the Boy break free and are instructed by the villains to heads to Build Base, Michi is called to divert their attention (she, as well Hiroshi, finding hesitancy in harming either of them) but the Boy fires its arrows at the Big Shooter, confusing it with a huge Pterodactyl, and is able to bring the aircraft down. Hiroshi is recall to then confront the Mammoth and the Boy.

The Two Prehistoric Friends arrive on Build Base (confusing the structure as a gigantic sauropod in their illusion) when Jeeg calls out to them; they charge at the Mecha, the latter avoiding them, not wanting to harm them, as he found them not at fault for their actions, specially the boy. His father reminded him both are stuck thinking they are in the past with no way to make the Boy understand. With the Mammoth coming for another attack, and seeing Emperor Dragon's face, Jeeg impales the creature with his Spear and Mammu falls, bringing distress to the Boy. However, in one last burst of energy, Mammu stands up, rams Jeeg and runs straight to the Water Basin with the Boy – both jump into it and sink to the bottom of the lake, where the Magic that brought them back to life finally dissipates and the two friends revert back to their Skeletal Forms.

Later, out on the lake in a boat, Hiroshi and Michi pour flowers over their new Resting Site, berating Dragon for his deed and hoping the two Ancient friends can now rest in their Dreams Forever.

Quick Note: Can it be said this was a really sad Bitter Sweet Episode? Cause this one ranks as my favorite of the series.