Need help identifying this little critter!

[Raazka]

I noticed this little orange-thing while checking out my tank today, thought it was a sponge at first but when I came back to look at it later it was moving and had revealed two little antennas! It only has two colours, orange that fades into a darker orange/brown towards the body, has a clam lip-like back and is super tiny. Any idea what it could be?

 

[56longroof]

Almost looks like a nudibranch of some sort.

 

[Sumbub]

It really does look like a nudibranch. Is it moving around like a slug?

 

[Raazka]

It really does look like a nudibranch. Is it moving around like a slug?

Yes, slides around slowly and moves its head/antennas

 

[ISpeakForTheSeas]

That's and Elysia species sacoglossan slug; either Elysia flava or Elysia obtusa:

Elysia flava or E. obtusa - harmless/beneficial Sacoglossan slugs. They're herbivores, with E. obtusa known to feed on Bryopsis, while E. Flava is thought to feed on Cladophora.

it seems at least some adults of some species can survive feeding on algae that isn't their preferred food, but juveniles cannot

 

[Raazka]

That's and Elysia species sacoglossan slug; either Elysia flava or Elysia obtusa:

Thank you so much!