Rift Eye in Steal an Egg

Rift Eye is a Rift pet (Legendary rarity). Rift pets do not come from a zone nest: they are obtained through the Rift event — timed Overlord fights every 30 minutes, the Boss Shop, Boss Mastery rewards, or the permanent Rift, which rotates through three egg banners roughly every 3 hours.

Base income is $11K/s. Among the 17 pets tagged Rift on the wiki that puts Rift Eye at number 17 — Shattered Colossus tops the Rift group at $3.5B/s. Remember the game multiplies this base by the size roll and by the mutation, so two Rift Eyes can earn very different amounts.

With a colour mutation and no size bonus, the same Rift Eye would earn roughly: Silver ×1.2 ≈ $13.20K/s, Golden ×2.5 ≈ $27.5K/s, Rainbow ×3.5 ≈ $38.5K/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.

Neither a hatch reward nor a grow time is recorded on the wiki for Rift Eye yet; if you have hatched one, the timer on the pen and the reward pop-up are the two numbers worth noting.

Legendaries are where a Golden or Rainbow roll starts changing your income bracket; guard the pen.