Do I have black bugs or beneficial creatures

[midwest reefs]

I recently started noticing these black moving creatures on the topmost rock work closest to the light. I have a GSP and they are not on it, they are seemingly only on the top rocks. Can someone help me identify them, please!

 

[CryptoNautical]

I've only seen these tiny creatures in the beginning of my reef tank. They only lasted about 4 days and then disappeared. I'd just sit back and let the tank age

 

[midwest reefs]

Okay, that's good to hear! I'll do just that. Thanks a lot!