Crocodile in Steal an Egg

Crocodile (Epic rarity) belongs to the Jungle zone. Jungle is zone 4 of 12 on the wiki's Biomes list; the wiki lists its entry requirement as 40K speed, and the nests there are watched by the Tiger. You get it by carrying the Crocodile Egg back to your pen.

At $420/s base income, Crocodile sits 6th out of 8 in its zone — King Snake tops the Jungle at $3.5M/s. The listed figure assumes no mutation and a normal weight.

With a colour mutation and no size bonus, the same Crocodile would earn roughly: Silver ×1.2 ≈ $504/s, Golden ×2.5 ≈ $1.05K/s, Rainbow ×3.5 ≈ $1.47K/s (multipliers from the wiki's Mutations page; arithmetic is ours). Add a Giant (×3) or Huge (×5) size roll on top and the numbers multiply again.

Hatching it pays a one-off reward of +9k Speed, $42k, and the egg takes 1m to grow in the pen. That reward is the reason low-income eggs are still worth stealing early: the speed bonus is what gets you into the next zone.

Epics are the mid-tier of their zone — a good candidate for your first mutation roll because the base rate is high enough to matter.