ID Please? Anyone ever seen these in their tank?

[Semper.Reefing]

I see these little guys fluttering around and was wondering if anyone could help me ID them. I was thinking they were some sort of shrimp. Thanks!

 

[WalkerLovesTheOcean]

Hard to tell but they look like some sort of nudibranch...

 

[Semper.Reefing]

Hard to tell but they look like some sort of nudibranch...

I should have mentioned they are floating in the water column

 

[ISpeakForTheSeas]

I should have mentioned they are floating in the water column

They're crustacean larvae of some kind; I would guess either hermit crab or shrimp larvae, but what crustaceans do you have in your tank?