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[Tmmart0625]

Recently I found a jelly fish and a peanut worm, but I am having trouble identifying this yellowish object that continuously moves around on the glass of my tank. Today I have found a similar yellow dot... what is this?

 

[Crabs McJones]

First two are a hydroid
The rest I cant really tell. I see.a spirorbid worm, but cant make out the other object

 

[cristata.reef]

It's a type of Labyrinthula. Feel free to look it up cause it's really hard to explain what it is (not an animal, plant, protist, etc). Should be harmless unless you want to keep sea grasses in which case it becomes a pathogenic agent that causes browning and necrosis in the leaves