4 Critter ID. Jellyfish in reef tank? Or hydroid polyp?

[cvin17]

Image 1: I assume this is aiptasia but wanted to be sure.

Image 2: What is this behind the xenia?

Image 3: These came on the live rock I just bought not sure what they are.

Image 4: Jellyfish or hydroid polyp?

 

[DSC reef]

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[cvin17]

Here's the link to the jellyfish hydroid video.
Image 4: Jellyfish or hydroid polyp?