Bronto in Steal An Egg

Cosmic · wiki data synced Oct 24, 2026

Bronto is a Cosmic pet that earns $1.5M/s at its base size of 35,000 kg. It hatches from eggs stolen in Prehistoric, where about 1 in 14 eggs is a Bronto egg (6.995959%).

It is #137 of 236 pets by base income, and #4 of 8 in Prehistoric.

Rarity: Cosmic
Base income: $1.5M/s
Base size: 35,000 kg
Zone: Prehistoric
Speed needed: 17M – 18M
Egg: Bronto Egg
Drop chance: 7%
Grow time: 11m
Reward: +300k Speed, $150m

How to get Bronto

Train until you have at least 17M – 18M Speed, then go to Prehistoric, zone 8 of 14, guarded by the T-Rex. Steal eggs there and bring them back to your base to hatch.

Each egg that spawns in Prehistoric has a 6.995959% chance to be a Bronto Egg. That means you need to see about 10 eggs for a 50% chance of at least one, and 32 eggs for 90%.

A Bronto egg takes 11m to hatch, and the wiki lists its reward as +300k Speed, $150m.

Bronto value by size and mutation

Income grows with weight but slows down past 125× the base size. These are the wiki's formula at three sizes:

Size	Normal	Golden ×2.5	Rainbow ×3.5
35,000 kg (base)	$1.5M/s	$3.75M/s	$5.25M/s
350,000 kg	$6.21M/s	$15.5M/s	$21.7M/s
3,500,000 kg	$25.7M/s	$64.2M/s	$89.8M/s

Work out your own Bronto: open it in the income calculator. All multipliers are on the mutations page.

How Bronto compares

By base income Bronto is #137 of 236 overall and #27 of 36 Cosmic pets. Just above it: 67 ($1.55M/s); just below: Crawler ($1.5M/s).

Other pets in Prehistoric

Pet	Rarity	Base $/s	Drop chance
Dodo	Rare	$280/s	39.1%
Pterodactyl	Legendary	$22K/s	26%
Ankylosaurus	Mythic	$120K/s	20.8%
Bronto	Cosmic	$1.5M/s	7%
Triceratops	Cosmic	$1.2M/s	4.93%
T-Rex	Secret	$25M/s	0.99% (1 in 101)
Tralaledon	Secret	$32M/s	0.83% (1 in 121)
Mosasaurus	Eternal	$180M/s	0.31% (1 in 321)

Source: Bronto on the Steal An Egg Wiki (CC BY-SA). First listed on the wiki Sep 4, 2026, during the Monsters Are Coming week. Synced Oct 24, 2026.