Unknown creatures/egg cases on glass of brackish opal ula tank

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towerkzar

Aquarium Advice Apprentice
Joined
Mar 23, 2025
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Location
south carolina usa
These are microscopic views of something populating the glass and some artificial plants in a 5 gallon brackish tank I’m preparing. There are no shrimp yet, but I do have Nerite and Nassarius Vibex snails which are very active. In the last 4 days these micro specks have appeared. They are approximately 1/4 mm in size, only visible in my digital microscope at high magnification. They do not move at all which leads me to believe they are very tiny egg cases of some kind. An online image search has not been helpful in identifying these. I hope someone here will know what we are looking at.
Thanks.
 

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I believe you are correct that this is an egg casing but not from anything I've seen before. On the other hand, with the one side being open and the other side appearing to be a suction or holding side, they could also be a type of sea squirt ( tunicate) with eggs inside. If you used natural sea water or anything directly from the wild, the gambit is wide open as to what it is/ they are. ;)
 
I used distilled water and marine salt from petshrimp.com, nothing from a marine or fresh water source.
Then is may have been a hitchhiker in with the snails or their water. It doesn't look like anything that would come from a municipal water source unless it's coming from a river or reservoir and not being sterilized before going out to the public. OR, did you have any live plants in the tank?
 
If that's the case, it's either from your water or from a snail. Snails have been known to be infested with all kinds of parasites so it ranks high on the possibility list. (y)
 
Whatever hatches out will be almost invisibly small considering the case is about .009” long, I certainly hope it’s nothing that could harm the opae ula shrimp when I get them. Interestingly i noticed when the snails crawl over them on the glass, they dont eat or even dislodge them.

Thanks for your comments!
 
It might be worth trying to remove them before they hatch. You can always leave them in a container of water to see what hatches. (y)
 
They look like nerite eggs to me. They don’t hatch in freshwater and I’ve had my snail lay eggs all over. If you try to scrape them off and they are stuck pretty good, it’s definitely nerite.
 
I did some careful scraping, and these egg cases (for lack of a better term), fall off the glass with the slightest touch. As you can see from the images, they are just a hollow translucent tube with no visible attachment structure. Even on the plants, if I lightly touch them with the tip of a bamboo skewer, they drift away. If anything has hatched from them since this started, there is no visible sign at this point, but they would probably be too small for quite a while considering the microscopic size of the eggs. Both the Nerite and zombie snails in the tank are active and don't seem to be suffering from some deadly parasite, which I was concerned those might be. It sure seems strange to me that I have not found any similar pictures online of translucent egg cases like these, they are really very distinctive looking, but I will keep searching.
 
I did some careful scraping, and these egg cases (for lack of a better term), fall off the glass with the slightest touch. As you can see from the images, they are just a hollow translucent tube with no visible attachment structure. Even on the plants, if I lightly touch them with the tip of a bamboo skewer, they drift away. If anything has hatched from them since this started, there is no visible sign at this point, but they would probably be too small for quite a while considering the microscopic size of the eggs. Both the Nerite and zombie snails in the tank are active and don't seem to be suffering from some deadly parasite, which I was concerned those might be. It sure seems strange to me that I have not found any similar pictures online of translucent egg cases like these, they are really very distinctive looking, but I will keep searching.
You may want to put a casing in a separate container for it to hatch in there so you can see what is coming from it. It may be you have a new discovery. (y) (y)
 
Those eggs have hatched and now there is an odd cone of swimming micro creatures in the center top of the tank. There is no filter running so their movement is self generated. I will try to pipette some out of the water to photograph them but I’m not optimistic.
 

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