Good elf or bad elf? ID help

[Nickles]

I noticed what I believe is an isopod recently swimming in my tank the other night and then today I saw it again sitting on a zoa frag.  I was able to remove the plug and discovered a second one.  I've been trying to Google for an ID but I figured I would post a couple pictures here in case anyone knows if I should be concerned.  The grid beneath them in the photo is made of 1/4" squares.  I based my isopod description on this article that I found referenced on many posts.

 

[Tetra1]

Saw these guys on another forum, don't remember the name of them, but, the person said they are harmless unless there are a lot of them.  I would try and get them out if you see them.  I don't like to take chances when a lot of money has been put into a tank.  Just my two cents.