Steal an Egg · Pet
Bronto
Bronto is a Cosmic pet in Steal an Egg that earns a base $1.5M/s. It hatches from the Bronto Egg, stolen from the nests of the Prehistoric biome.
EggBronto EggPet stats
Base income
$1.5M/s
Base weight
35,000 kg
Egg
Bronto Egg
Grow time
11m
Speed reward
+300K
Cash reward
$150M
Source
Prehistoric
Biome nest
Rarity
Cosmic
Where to get Bronto
Steal the Bronto 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
Bronto income with mutations and size
| Mutation | 1× weight35,000 kg | 10× weight350,000 kg | 100× weight3,500,000 kg | 200× weight7,000,000 kg |
|---|---|---|---|---|
| No mutation×1 | $1.5M/s | $6.21M/s | $25.7M/s | $35.5M/s |
| Rainbow×3.5 | $5.25M/s | $21.7M/s | $89.8M/s | $124M/s |
| Parasite×3 | $4.5M/s | $18.6M/s | $77M/s | $107M/s |
| Fractured×2.75 | $4.13M/s | $17.1M/s | $70.6M/s | $97.8M/s |
| Scrambled×2.75 | $4.13M/s | $17.1M/s | $70.6M/s | $97.8M/s |
| Golden×2.5 | $3.75M/s | $15.5M/s | $64.2M/s | $88.9M/s |
| Spirit Bloom×2.5 | $3.75M/s | $15.5M/s | $64.2M/s | $88.9M/s |
| Bloom×1.25 | $1.88M/s | $7.76M/s | $32.1M/s | $44.4M/s |
| Silver×1.2 | $1.8M/s | $7.45M/s | $30.8M/s | $42.7M/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 Bronto compares
Neighbors by income in Prehistoric (5 of 8):
Other Cosmic pets
Bronto guide
The Bronto is the heavyweight of Prehistoric in the literal sense. Its base weight of 35,000 kg is the highest in the zone, above even the Eternal Mosasaurus at 30,000 kg, and ten times the Triceratops that shares its Cosmic rarity.
Bronto Egg: where and how long
- Biome: Prehistoric, 8th in the biome order
- Speed requirement: 18M
- Guardian: T-Rex
- Growth: 11 minutes
- Reward: +300k Speed and $150m
One oddity in the data: the Bronto's +300k Speed reward is lower than the Triceratops' +360k, even though the Bronto earns more and takes longer. If your goal for an egg is Speed rather than income, the Triceratops returns more for less waiting.
Income and rank
At $1.5M/s the Bronto is the highest earner in Prehistoric before the Secret tier begins with the T-Rex at $25M/s. It ranks 5th of 8 in its zone, 10th of 28 Cosmic pets, and 89th of 198 overall, counting from the lowest earner.
The $150m hatch payout covers the Golden Treadmill ($120M) with about $30m left over.
Size makes the difference
The wiki says bigger eggs carry a higher value multiplier but slow you down, and with a base weight this large, carrying a big Bronto away from the T-Rex is a real consideration. The payoff, using the wiki's documented formula (marked beta there):
- Golden: about $3.75M/s
- Rainbow: about $5.25M/s
- 10× base weight: about $6.21M/s
- 100× base weight: about $25.7M/s
- Rainbow with 100× weight: about $89.8M/s
A 100× Bronto would slightly outearn an unmutated T-Rex.
Sacrifice and Laboratory
It sits in the Hard tier of the Riftbeasts and Shattered Rift sacrifices, and the Laboratory's Biohazard banner lists it as a Cosmic pet from the Prehistoric egg.
Data sourced from the Steal an Egg Wiki (CC BY-SA) and processed automatically; last synced 2026-10-11.