critter id

What is this? I found it while cleaning out my sump. At first it looked like slime but then it started moving. Kind of looks like a snail without a shell or a nudebrach. Is it safe for my display tank? Will my mandarin eat it? so many questions....lol. picture is a little misleading but...

Alright guys I have two things I'm not sure what they are. One is a white, clearish looking slug snail thing maybe 1/8-1/4 of and inch. The second is a green slug worm looking thing 1/4-3/8 of and inch. I'm going to research some more after I post this but I've had no luck so hopefully you guys...

This guy has appeared in a friends tank and at first I thought some kind of sponge but not so sure now. Any id?

I found this small crab "living" on my small sea apple. It's white with black stripes and thin claws, kind of like an arrow crab. I've haven't seen anything like it. Can anyone help me in IDing it and letting me know if it's reef safe or something I should kick out pronto? Thanks!

Hello Newbie here, I purchased my tank a week ago Saturday (had been up and running for over 2 years with a clownfish, yellow tang and damsel) and about 2 days ago this translucent web stuff showed up on my LR. On one rock its gotten fairly big~ 2"x3" . Upon a closer inspection it appears to...

I am in a real mess right now.. I got small concentric ring shaped organisms on a piece of rock(harboring mushroom coral) from the LFS guy. these organisms were extremely light sensitive and would withdraw at once...(when i focus them with a torch light, they retreat into the hole). Initially...

I am in a real mess right now..:bawling: I got small concentric ring shaped organisms on a piece of rock(harboring mushroom coral) from the LFS guy. these organisms were extremely light sensitive and would withdraw at once...(when i focus them with a torch light, they retreat into the hole)...

i found this little guy on my live rock.......is it atipasia? or a glass anemone or what? (not the limpet) the thing with tentacles......if you look close under the limpet there is another 2 or three heads of this thing!!!!!!

Hi my brother has these in his tank and i was going to get some corals off him but i don't know now after i saw these thing can anyone tell me if they are good or bad and if bad how to get rid of them