Possibly an eel. Help

[Wilhelm]

It pokes about a half inch of its body out of a tunnel in the sand. It is eel like but about half the diameter of a common lead pencil. It has a small mouth, one eye on each side of the head. It is black with a blue ring around the head just behind the eyes. I see about half an inch but have no idea how LNG it might be. It is shy and quickly withdraws into its burrow on my approach. What could it be? The last rock put in my tank was a couple years ago. The last coral put in was a small brain coral put in about two months ago.

Help.

 

[LavaToad]

It sounds like it could be a type of watchman goby. Try googling "black watchman goby" or "naked goby" and see if it looks similar

 

[Wilhelm]

Great guess, my friend. I set a trap borrowed from a friend. It is an Engineer Goby several inches long. I can only guess that it arrived as a fertilized egg attached to a piece of coral. Thanks for your time and input.