Strange Macroscopic Red Bugs?

[lrunasiu]

Hello all! Any ideas what these little guys are? They are very tiny, smaller than a grain of sand. And are currently all over everything in my tank, but mainly on/in the sand bed. I am very curious to see if any of you know what they might be. They are small, red/purplish and have worm-like movement. I have attached a video showing them moving around. For context, these guys have just popped up in my 7 gallon nano from seemingly nowhere during a “dirty” dinoflagellate cleanse with a blackout and copepods. They popped up about 2-3 days in to the blackout. Thanks!

 

[lrunasiu]

Here is a link to the video on youtube as well if the other one doesn't work.
https://youtube.com/shorts/a-xPWwx8bNE?feature=share

 

[lrunasiu]

After a lot more research I am still failing to figure out what these little critters are, however I can now say after some more observation that they are benthic, and don't like the overhead lights. Seeming to only come out when the lights are off or hang out in more shaded areas of the tank. I pulled out my microscope and took another video of them under 100x zoom. Here is the video as well as it being attached below.
https://youtube.com/shorts/gxaGXFYKyY4?feature=share

 

[BlueFynn_Ian]

After a lot more research I am still failing to figure out what these little critters are, however I can now say after some more observation that they are benthic, and don't like the overhead lights. Seeming to only come out when the lights are off or hang out in more shaded areas of the tank. I pulled out my microscope and took another video of them under 100x zoom. Here is the video as well as it being attached below.
https://youtube.com/shorts/gxaGXFYKyY4?feature=share

I have the same critters that I just noticed in my tank as well. So far mine are only in my sump. Following to see if you get any answers.

 

[sculpin01]

I’m going to go with a macroscopic ciliate as my guess.