HELP ID PLEASE !?!?! Tiny White Transparent Shell & Black legs w/ Yellow Center Mass

[Sixty]

Was observing my tank at night and noticed white dots around the base of soft corals on the rock/frag plugs and the stony corals on the skeleton and the base of the rock/frag plugs, i grabbed my long spot feeding pipette and suck some off the rock, pulled out my microscope camera and took some videos, in the video you can see thy have white transparent shell and black legs/arms with a yellow center mass that you can see thru the shell also in the video you can see me use a toothpick to move it around that's how small thy are. Dose anybody know what these are and specially if thy are harmfull ?

 

[Sixty]

Was observing my tank at night and noticed white dots around the base of soft corals on the rock/frag plugs and the stony corals on the skeleton and the base of the rock/frag plugs, i grabbed my long spot feeding pipette and suck some off the rock, pulled out my microscope camera and took some videos, in the video you can see thy have white transparent shell and black legs/arms with a yellow center mass that you can see thru the shell also in the video you can see me use a toothpick to move it around that's how small thy are. Dose anybody know what these are and specially if thy are harmful ?

Forget about around the corals after posting this I went back to looking at the tank and thy are literally covering every inch of the sand, and rock. holy molly someone please help me ID this crustacean.

 

[El Toro]

Looks like a clam

 

[luilui]

Forget about around the corals after posting this I went back to looking at the tank and thy are literally covering every inch of the sand, and rock. holy molly someone please help me ID this crustacean.

Baby barnicle

 

[swervinscoot]

I agree with barnacle, maybe gooseneck barnacle babies? Being white like that.