Some kind of slug?

[hllb]

I’ve had several hitchhikers on this rock but this is the strangest! Has antenna, looks like a slug, slightly iridescent.

 

[Peach02]

I may be wrong but it looks like a abalone to me. Nothing to be worried about they are really good for algae but grow quite large

 

[Silver14SS]

Looks like a stomatella

Stomatella | Melev's Reef

Many people ask about a snail or slug with a half-shell on its back. They are called Stomatella, and are fast moving slugs. Their shell is similar to a fingernail in shape, which covers the head and torso of the creature. They are found moving about the rockwork especially at night, and are an...

www.melevsreef.com

 

[hllb]

Looks like a stomatella

Stomatella | Melev's Reef

Many people ask about a snail or slug with a half-shell on its back. They are called Stomatella, and are fast moving slugs. Their shell is similar to a fingernail in shape, which covers the head and torso of the creature. They are found moving about the rockwork especially at night, and are an...

www.melevsreef.com

That’s it! Stomatello. The first picture at that link looks exactly like mine. Cool! It’s amazing what you find when you aren’t distracted by flashy fish. My tank is only 3 weeks old so only one tiny fish and apparently a bunch of hitchhikers! I did add two peppermint shrimp and one already molted!

 

[Silver14SS]

Cool! It’s amazing what you find when you aren’t distracted by flashy fish. My tank is only 3 weeks old so only one tiny fish and apparently a bunch of hitchhikers!