Help!! What is this thing?

[Shoki]

Hello everyone!! I’ve not really had any issues with pests besides the pests i already know are present. Bristle worms, vermetid snails, asterina starfish.. possibly other small inverts i’m unaware of. Nothing is particularly munching on my corals.

I was looking at my tank with the lights off and noticed these barnacle looking things.
They were all over the top of the rock but not on the two corals i have on the rock.
Turned the lights on, left the room for about an hour, came back. Majority of them have moved !!!! Now i’m like okay… what are these?!?!?
Can anyone tell by these pictures?

 

[Doompastew]

IMO it's a flatworm

 

[ISpeakForTheSeas]

Hello everyone!! I’ve not really had any issues with pests besides the pests i already know are present. Bristle worms, vermetid snails, asterina starfish.. possibly other small inverts i’m unaware of. Nothing is particularly munching on my corals.

I was looking at my tank with the lights off and noticed these barnacle looking things.
They were all over the top of the rock but not on the two corals i have on the rock.
Turned the lights on, left the room for about an hour, came back. Majority of them have moved !!!! Now i’m like okay… what are these?!?!?
Can anyone tell by these pictures?

The last pic here makes it look like it is a critter with a snail-like foot and a hard shell - if that's accurate, then possibly a limpet or keyhole limpet (these have a hole on/near the pinnacle of their shells)?

That would seem to match well with the barnacle-like description.

 

[Shoki]

The last pic here makes it look like it is a critter with a snail-like foot and a hard shell - if that's accurate, then possibly a limpet or keyhole limpet (these have a hole on/near the pinnacle of their shells)?

That would seem to match well with the barnacle-like description.

Yes!! It has a snail/conch like foot, i’ve never seen any of these on the glass and they were covering legit the entire top surface of the rock. Has a barnacle shape shell, with a tiny hole at the peak of the point on the shell. I have soft and LPS corals and i don’t plan on having SPS in the future. i don’t have much algae on the rocks and my tank is only 6 months old. I looked up keyhole limpets but they seem to be a bit larger than what i have. Keyhole limpets or some other type of smaller limpet, are these a problem?

 

[ISpeakForTheSeas]

Yes!! It has a snail/conch like foot, i’ve never seen any of these on the glass and they were covering legit the entire top surface of the rock. Has a barnacle shape shell, with a tiny hole at the peak of the point on the shell. I have soft and LPS corals and i don’t plan on having SPS in the future. i don’t have much algae on the rocks and my tank is only 6 months old. I looked up keyhole limpets but they seem to be a bit larger than what i have. Keyhole limpets or some other type of smaller limpet, are these a problem?

If it has a hole (regardless of the hole's size, which varies greatly from one species to another), it's a keyhole limpet.

The vast majority of keyhole limpets are completely safe/beneficial - a few species from a couple of subfamilies are known to eat SPS corals:

Just to clarify this - there are multiple kinds of snails referred to as limpets (with a hole in the top of the shell, these are Keyhole Limpets):

True limpets are from the taxonomic subclass Patellogastropoda, and they're harmless/beneficial herbivores.

Keyhole limpets are fissurellid snails from the subclass Vetigastropoda; a handful of these snails from the taxonomic subfamilies Diodorinae and Emarginulinae are known to eat SPS:

t’s rare, but there are two taxonomic subfamilies of keyhole limpets (Diodorinae and Emarginulinae) that I have found research on showing that they have a handful of species in them that are either known to or thought to occasionally eat corals (I’d need to go digging through the papers again, but, IIRC, they only ate SPS , and they had pretty specific tastes/preferences).

just to reinforce, regular limpets are fine, and most keyhole limpets (including most from the subfamilies listed above) are reef safe; to the best of current scientific knowledge, only a very small number of them are not.