What is this (1 Viewer)

[Jhwku]

Purple in color has lips and looks like feathers in middle.

 

[Diesel]

Need a better pic!

I fear for a bad pest as your coral (purple bonsai) has some tissue loss right under that first branch which is close to that what we trying to figure out what we talking about.

 

[Jhwku]

Hard to get a clear picture it's so far back. All I can tell is it has purple lips blue feathers inside and maybe thorns when it closes. It protruded from the rock so i can't see base

 

[Diesel]

If it's possible take the rock out and try to remove it, what you describe doesn't sound friendly to me to corals.

 

[Jhwku]

Looks to have a foot

 

[Diesel]

If you try to touch it with something will it retracted back in the rock or will it take on a defends position?

 

[Jhwku]

It retracted

 

[Jhwku]

Looks to have small spikes

 

[Diesel]

That sounds to me like a nudibranch of some sort.
I would get it out ASAP.

 

[Diesel]

Coral Eating Nudibranchs - Aquarium Coral Diseases

acro eating nudibranchs - Bing images

large nudibranchs - Bing images

Nudi's are kinda cool as they come in so many colorful types but I won't trust any of them.

 

[Jhwku]

I'll do my best to get it out. These things always find the toughest spots

 

[Diesel]

Yes they do.
Good job spotting him or he would go slowly after some corals as you can see he already did.

 

[Cody]

When in doubt, get it out. Very few hitchhikers can munch your corals when they're in the bottom of your trash can.

 

[FarmerTy]

Elephant slug?

 

[Jhwku]

This is what it was after I removed it. It had a hard shell with small black spines. It broke my surgical knife so it ended up broken as well.

 

[Jhwku]

As for the coral there might be a second pest.

 

[FarmerTy]

Still sticking with my answer, black elephant slug limpet.

 

[notmyname]

Look more closely... if it has a shell (mantle nearly covers it), then it may be an elephant snail, which is not harmful.

Elephant snail?