What is this disc?

[voiceinthedesert]

I found this on the sand tonight. I picked it up and looked and dropped it again, assuming it was a limpit shell or something. Then, it shocked me by swimming to the glass, climbing it's way down to the sand again and chilling there. Picture is the best I can do, but it's definitely alive. Maybe a mm or two across. Looks like an orange disc with concentric circles on the underside.

 

[elysics]

nervermind, was wrong

 

[samnaz]

Weird... Any legs or tentacles? Was it hard like a shell? I can think of nothing round that can swim other than a jellyfish or medusa hydroid.

 

[voiceinthedesert]

It looks like it has very small filaments coming off it. Hasn't moved since last night.

 

[vetteguy53081]

Pic very blue. Looks like chalice but need better pic with white lights to confirm

 

[samnaz]

It looks like it has very small filaments coming off it. Hasn't moved since last night.

Can you get a pic of it under whites?

 

[mtfish]

Very blue picture but at 1 or 2 mm, I am thinking some type of ostracod?