I need some critter ID please?

[Xerxes_Zoanthids444]

Idk what these are and if they are reef safe?

Will this hurt my reef?

 

[saltyphish]

Interesting maybe a type of nudibranch. Lets see what others think

 

[Sm51498]

sort of looks like a cucumber to me, how fast does it move? typically cucumbers are slow, nudis are still slow but tend to be faster.

 

[nicks nano reef]

Yeah that's a Cucumber, I've had many similar to the ones pictured in the past. They are similar to Lions paw, or medusa sea Cucumbers or , in my experience they are completely reef safe and extremely effective detritivores.
I found a post on wet web media that may be of some assistance