The Prehistoric anchor
The Mosasaurus is a huge sea reptile from the Prehistoric biome, hatched from what players call the monstrous egg, the best egg the T-Rex guards. It's the pet that carries most accounts through the long grind from 18M to 700M speed, and eternal versions also appear in rifts. One creator, opening one for the first time, said "we've got baby shark now".
Income readings
| Copy | Income |
|---|---|
| Tiny | $7.4M |
| Average | $139M |
| 24,000 kg | $159M |
| Basic (creator test) | $180M |
| Golden | $450M |
| Rainbow | $630M |
| Medium fused | $744M |
| Massive (server reset) | $2.3B |
That $7.4M-to-$2.3B range is a reminder: Mosasaurus value is mostly size. "That thing is tiny… this guy does 2.3 billion. He also makes the base. And the other Mosasaurus obviously doesn't come nowhere near making the base. 7.4 million is crazy."
How to get one
- Prehistoric nests (18M speed). Small eggs are fine at the sign; big ones need much more.
- Eternal Mosasaurus rifts. At night a rift can open with an eternal Mosasaurus egg: "A rift spawned… an eternal Mosasaurus egg. No way." Free-to-play accounts also found eternal Mosasaurus eggs sitting in the Prehistoric they couldn't yet reach.
- Server resets for massive ones.
The egg takes about 6 hours. Plant it at dusk.
Beating the T-Rex for one
Getting a big Mosasaurus home is the classic Prehistoric struggle. One player at 18.1M failed repeatedly, still got caught at 50M, and finally made it at about 70M with a better trail. Tips:
- Overshoot the sign heavily before trying big eggs.
- Steal while the T-Rex chases someone else.
- Use the drop-and-pick-up trick.
Fusing Mosasauruses
Because they're common, Mosasauruses are great Fuse Machine fodder. A server-hop player fused their smallest ones: "We can fuse some Mosasaurus to try to get an even bigger one… 23,000 kg, I think that's the smallest one." Results were "kind of midsize", which was still useful.
Where it sits
B tier. It's your best friend between Prehistoric and Cosmic, and a massive or eternal one can hold a pen well into the late game. Once you have divines, average Mosasauruses fall out of Equip Best.
Mosasaurus FAQ
Is the Mosasaurus a secret or an eternal? The rift version is eternal, and the best Prehistoric egg is commonly called the monstrous egg. Either way, it's the top Prehistoric pet.
Why do two Mosasauruses earn so differently? Weight again: $7.4M for a tiny one, $2.3B for a massive one.
Should I mutate one? Rainbow took a $180M Mosasaurus to $630M. Worth it in the mid-game if it's your heaviest egg; skip it once you have divines.
Can I farm Mosasauruses at night? You can't steal at night, but it's the best time to grow the eggs you already have, and a good time to watch for rifts.
Quick facts
- Rarity: Eternal (best Prehistoric egg; eternal rift versions)
- Biome: Prehistoric (18M speed)
- Hatch time: about 6 hours
- Typical income: $139M–180M
- Best seen: $2.3B (massive)
Related: Prehistoric biome, speed guide, fusion guide, Lunar Dragon.