---
title: Miraculous Egg-eater (Favorinus mirabilis)
scientific_name: Favorinus mirabilis
common_name: Miraculous Egg-eater
taxon: Nudibranch
published: 2026-08-27T21:09:41.041Z
updated: 2026-08-27T22:43:49.762Z
tags: Miraculous Egg-eater, Favorinus mirabilis, Nudibranch, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch/miraculous-egg-eater
---

# Miraculous Egg-eater (*Favorinus mirabilis*)

## Quick facts

- **Group:** Nudibranch (*Nudibranchia*)
- **Size:** up to 1.2 cm
- **Diet:** Molluscivore
- **Activity:** Cathemeral
- **Rarity:** Rare
- **Habitat:** Reef and rubble, on the egg ribbons of other sea slugs
- **Reproduction:** Simultaneous hermaphrodite, Egg layer

## How to recognise it

- a long yellow streak running between the two rhinophores
- rhinophores dark brown, and swollen along their length like beads
- twelve millimeters, the smallest of the three egg-eaters here
- found on a coiled egg mass rather than on sponge or coral

Three species on this one reef make their living the same way: they find the egg ribbons of other sea slugs and eat them. That is worth pausing on. A niche has to be reliably productive to support one specialist, and this one supports three side by side, which tells you how much spawn is sitting on a reef at any moment. Sea slugs lay coiled ribbons of thousands of embryos, glue them to rock or sponge, and leave. Nobody guards them. It is the most defenseless concentrated protein on the reef.

The genus is built for finding it and marked so you can recognize it: the rhinophores are swollen into beads along their length, which no other slug here carries.

This is the small one, twelve millimeters (0.5 in), and its own mark is a long yellow streak running between those dark brown rhinophores, on the head between the horns. Its two relatives here are told apart by black-tipped cerata and by cerata that change color to match whatever eggs the animal has been working through.

One consequence of the diet is worth stating. Aeolids normally eat stinging animals and keep the unfired capsules as their own weapons. An egg ribbon contains nothing of the kind. These three eat extremely well and come away from every meal with nothing to defend themselves.

## Also known as

- **English:** Miraculous Egg-eater
- **Japanese:** ウツセミミノウミウシ
- **Chinese:** 美麗灰翼海蛞蝓
- **Russian:** Фаворинус удивительный

## Range

Mozambique, Sagami Bay

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch/miraculous-egg-eater)*
*Updated: August 27, 2026*