Tiny green critter ID?

[pik]

Couldn't get a decent still picture. This is a frame grab from a video (which won't upload). The perspective is looking up at the surface, with their little green bodies reflecting off the surface.

When I turn off pumps to feed, these little green critters gather at the surface under the brightest area of light and jerk around. About the size of copepods, but distinctly green and never see them on the glass. My best guess is hermit crab larvae, which I've had before, but these are a vibrant green and have lasted at least week so far whereas most larvae in my tank are usually gone in a day or two. What are they?

Other inhabitants of tank:
1 x Flame Angel
1 x Yellow Tang
1 x Tomato Clown (lays eggs)
1 x Pincushion Urchin
1 x Lawnmower Blenny
Scarlett Reef Hermit Crabs
Cerith Snails

 

[sfin52]

See attached video. Couldn't get a decent still picture. The perspective of the video is looking up at the surface, with their little green bodies reflecting off the surface.

When I turn off pumps to feed, these little green critters gather at the surface under the brightest area of light and jerk around. About the size of copepods, but distinctly green and never see them on the glass. My best guess is hermit crab larvae, which I've had before, but these are a vibrant green and have lasted at least week so far whereas most larvae in my tank are usually gone in a day or two. What are they?

Other inhabitants of tank:
1 x Flame Angel
1 x Yellow Tang
1 x Tomato Clown (lays eggs)
1 x Pincushion Urchin
1 x Lawnmower Blenny
Scarlett Reef Hermit Crabs
Cerith Snails

No video

 

[sfin52]

Sounds like lettuce nudibranch

 

[pik]

Here's the video finally.



Seen from below, nipping at the surface, reflection makes them look like two lobes but it's just one.

 

[sfin52]

Hmm @fishguy242 @Eagle_Steve @Lost in the Sauce thoughts.

 

[fishguy242]

hi, type of hydroid ??

 

[pik]

hi, type of hydroid ??

FWIW I haven't added anything to the tank in over a year. These just showed up recently.

 

[pik]

I got a digital microscope and a much better view. Spherical little jellyfish looking thing. Less than 1mm long. ID?