Steal an Egg · Pet
Mosasaurus
Mosasaurus is an Eternal pet in Steal an Egg that earns a base $180M/s. It hatches from the Mosasaurus Egg, stolen from the nests of the Prehistoric biome.
EggMosasaurus EggPet stats
Base income
$180M/s
Base weight
30,000 kg
Egg
Mosasaurus Egg
Grow time
6h
Speed reward
+600K
Cash reward
$18B
Source
Prehistoric
Biome nest
Rarity
Eternal
Where to get Mosasaurus
Steal the Mosasaurus Egg from the nests of the Prehistoric biome, carry it back to your pen and let it hatch.
- Speed required
- 18M
- Guardian
- T-Rex
The guardian sleeps next to the nest; the faster you are, the easier it is to outrun it. Bigger eggs are worth more but slow you down. Eggs & guardians
Estimate based on the wiki formula
Mosasaurus income with mutations and size
| Mutation | 1× weight30,000 kg | 10× weight300,000 kg | 100× weight3,000,000 kg | 200× weight6,000,000 kg |
|---|---|---|---|---|
| No mutation×1 | $180M/s | $745M/s | $3.08B/s | $4.27B/s |
| Rainbow×3.5 | $630M/s | $2.61B/s | $10.8B/s | $14.9B/s |
| Parasite×3 | $540M/s | $2.23B/s | $9.24B/s | $12.8B/s |
| Fractured×2.75 | $495M/s | $2.05B/s | $8.47B/s | $11.7B/s |
| Scrambled×2.75 | $495M/s | $2.05B/s | $8.47B/s | $11.7B/s |
| Golden×2.5 | $450M/s | $1.86B/s | $7.7B/s | $10.7B/s |
| Spirit Bloom×2.5 | $450M/s | $1.86B/s | $7.7B/s | $10.7B/s |
| Bloom×1.25 | $225M/s | $931M/s | $3.85B/s | $5.33B/s |
| Silver×1.2 | $216M/s | $894M/s | $3.7B/s | $5.12B/s |
Estimate based on the wiki formula (marked beta there): income = base × (weight ÷ base weight)^(37/60) × mutation, with diminishing returns above 125× the base weight. In-game values can differ. See mutations and the income calculator.
How Mosasaurus compares
Neighbors by income in Prehistoric (8 of 8):
Earns less
Tralaledon
$32M/s(÷5.63 vs Mosasaurus)
Other Eternal pets
Mosasaurus guide
The last and largest prize in Prehistoric is the Mosasaurus, the zone's Eternal, earning $180M/s, more than five times the Tralaledon just below it.
Six hours in the pen
The Mosasaurus Egg spawns in Prehistoric, the 8th biome, behind an 18M Speed requirement and the T-Rex guardian. It needs 6 hours to grow. In return it pays the zone's largest hatch reward: +600k Speed and $18b.
Six hours makes it an overnight or long-session egg. The $18b on its own is close to the price of the Galaxy Trail (20B, 5×), so one hatch gets you most of the way there.
Next to the ocean's Eternal
Players arriving from Abyss Ocean will recognise the pattern from El Maja:
- El Maja: $130M/s, 5h 30m, +180k Speed, $13b
- Mosasaurus: $180M/s, 6h, +600k Speed, $18b
For half an hour more, the Mosasaurus earns about 38% more and gives more than three times the Speed. Among Eternal pets it ranks 20th of 24, and 61st of 198 overall.
Size and mutation outlook
Its base weight is 30,000 kg. Based on the formula the wiki documents (with its calculator still marked beta), the estimates are:
- Golden: about $450M/s
- Rainbow: about $630M/s
- 10× base weight: about $745M/s
- 100× base weight: about $3.08B/s
- 200× base weight: about $4.27B/s
- Rainbow and 100× weight: about $10.8B/s
Next step
The next biome, Cosmic, needs 700M Speed. The +600k from a Mosasaurus helps, but treadmills and trails will cover most of that distance; the egg's cash is what pays for them.
Data sourced from the Steal an Egg Wiki (CC BY-SA) and processed automatically; last synced 2026-10-11.