What is this blob?

[Runningfanatic]

Here's my story. Tank is 75 gal and 10 years old. I have not added anything to it for close to 3 years (a fish at that time) except nassarius snails (big mistake, as I now have 100s of them!). I can't even remember the last time I added any rocks. I went through dinos for about a year (2021) (thanks Vibrant). I let the nutrients get very high (N > 100, P = .59). Started carbon dosing about 6 months ago. Things are looking great so far. I have only 4 small fish, mushrooms and gsp. Plan is to get my tank "perfect" and start adding more corals sometime next year. Currently N=25 and P=.08. Alkinity, pH, calcium, have all been stable in acceptable ranges.

A while ago, I noticed a "blob" growing in the substrate. It has gotten bigger with time and is currently about 2 inches in diameter. It looks like something that has attached to pieces of the substrate and then glued itself into one cohesive item. I have attached a picture taken with just daylight showing little tubes coming up and out. I've also attached a video showing tentacles flowing with the water movement. It has no real color. Does anyone have a clue what this thing is? I'm stumped, as I've never seen anything like this before. Any help is appreciated.

 

[jabberwock]

Useless, but following

 

[WheatToast]

Definitely a sponge, possibly of the Clathrina genus. These harmless filter-feeders normally attach to rockwork. I've never seen "slime" come out of these sponges, though.
Somewhat unrelated, but do you have pictures of the Nassarius snails?

 

[theMeat]

Hmm

 

[Dburr1014]

I agree that it's a sponge.

 

[vetteguy53081]

Sponge that will likely grow and offer no benefits in which you can remove now.
I believe its a filter feeder and may be of use in sump, but ive seen this twice and discarded it

 

[Runningfanatic]

Definitely a sponge, possibly of the Clathrina genus. These harmless filter-feeders normally attach to rockwork. I've never seen "slime" come out of these sponges, though.
Somewhat unrelated, but do you have pictures of the Nassarius snails?

Here's a picture and short video of them. They came out within seconds of me adding brine shrimp to the tank. Gotta admit, I have no idea what to do with them; there's just too many! This is just my 10 gal nano (I think there's probably 50-100 of them in there!). Pretty sure my 75 gal has a million of them!

 

[WheatToast]

Here's a picture and short video of them. They came out within seconds of me adding brine shrimp to the tank. Gotta admit, I have no idea what to do with them; there's just too many! This is just my 10 gal nano (I think there's probably 50-100 of them in there!). Pretty sure my 75 gal has a million of them!

Awesome! Nassarius eggs aren't too uncommon, but you don't normally see them reach adulthood since the planktonic juveniles are easily captured by filters and predators. Perhaps these are not true Nassarius snails (and they certainly don't look like any of the common species in the trade), though the genus is highly varied so there's always a chance.
@ISpeakForTheSeas
How's the sponge blob?

 

[ISpeakForTheSeas]

Awesome! Nassarius eggs aren't too uncommon, but you don't normally see them reach adulthood since the planktonic juveniles are easily captured by filters and predators. Perhaps these are not true Nassarius snails (and they certainly don't look like any of the common species in the trade), though the genus is highly varied so there's always a chance.
@ISpeakForTheSeas
How's the sponge blob?

I'm not sure what species this is (and there are way too many species in the genus for me to feel confident in my ability to narrow the list down enough to find it), but I did find out that there are some Nassarius species (such as the Japanese Nassa, N. fraterculus) which have benthic larvae.

OP, the fact that yours are reproducing freely in a tropical tank is really cool (regardless of if they actually are Nassarius snails or not). Have they caused any issues for you, particularly with other snails, or have they just been beneficial CUC?

 

[Runningfanatic]

Awesome! Nassarius eggs aren't too uncommon, but you don't normally see them reach adulthood since the planktonic juveniles are easily captured by filters and predators. Perhaps these are not true Nassarius snails (and they certainly don't look like any of the common species in the trade), though the genus is highly varied so there's always a chance.
@ISpeakForTheSeas
How's the sponge blob?

The blob is still there. But, what I originally thought were small tentacles are probably just a slime, as suggested. I say that because it appears to be getting longer. I think I'm just going to take it out. To me slime means it's dying.

 

[Runningfanatic]

I'm not sure what species this is (and there are way too many species in the genus for me to feel confident in my ability to narrow the list down enough to find it), but I did find out that there are some Nassarius species (such as the Japanese Nassa, N. fraterculus) which have benthic larvae.

OP, the fact that yours are reproducing freely in a tropical tank is really cool (regardless of if they actually are Nassarius snails or not). Have they caused any issues for you, particularly with other snails, or have they just been beneficial CUC?

I have not had any issues with these snails, other than there are just a LOT of them! Lol Too bad they don't eat algae...I could use a glass cleaner!