Huge black slug id in declining tank

[Jelpin16]

Hello all,

My tank has been struggling recently after months of the best growth ive ever had. I had an 1.0 alk swing and things suffered starting 1-2 months later. Sps, lps, polyp bail and bleaching. One of my rocks was moved tonight and I went to move it back and noticed a big patch of black sponge!

....which then moved. After 20 minutes of trying to pry or coax it off I removed the slug. It clings extremely well is quite thick and has a "skirt" going around its body. It has 2 eye stalks and can move quite fast. Does anyone have an id or insight if he may have been targetting my corals? I sent out an icp and levels are all where they need to be. Pics of coral damage and slug below, finger for scale.

 

[EeyoreIsMySpiritAnimal]

Can you post a clearer picture of the "top" of the critter?

 

[Tamberav]

Hello all,

My tank has been struggling recently after months of the best growth ive ever had. I had an 1.0 alk swing and things suffered starting 1-2 months later. Sps, lps, polyp bail and bleaching. One of my rocks was moved tonight and I went to move it back and noticed a big patch of black sponge!

....which then moved. After 20 minutes of trying to pry or coax it off I removed the slug. It clings extremely well is quite thick and has a "skirt" going around its body. It has 2 eye stalks and can move quite fast. Does anyone have an id or insight if he may have been targetting my corals? I sent out an icp and levels are all where they need to be. Pics of coral damage and slug below, finger for scale.

It is a limpet. I had a black one and an orange one, they ate algae only for me.

 

[Jelpin16]

Can you post a clearer picture of the "top" of the critter?

This was a pic before taking it out of the tank, not great though. I will try to get one in the am

 

[EeyoreIsMySpiritAnimal]

It is a limpet. I had a black one and an orange one, they ate algae only for me.

That's what I suspected but couldn't tell from the pics. Fleshy limpet then?

 

[Tamberav]

https://nudibranch.com.au/pages/8163a.htm

algae grazer - GOOD guy

 

[Jelpin16]

It is a limpet. I had a black one and an orange one, they ate algae only for me.

You

That's what I suspected but couldn't tell from the pics. Fleshy limpet then?

Did some quick searching possibly keyhole limpet or elephant slug which is still a limpet?

Its shell would be exposed like a thin white slit on its back if it moved the right way.

 

[Tamberav]

You

Did some quick searching possibly keyhole limpet or elephant slug which is still a limpet?

Its shell would be exposed like a thin white slit on its back if it moved the right way.

They are the same thing just different names.. they are also called scutus.

Scutus antipodes looks like

 

[EeyoreIsMySpiritAnimal]

Elephant slugs are just one variety of keyhole limpet. Many keyholes seen in the hobby don't have the large fleshy mantle and the shell is more prominent.