Weird little animal found in the tank

[equinom]

I found this weird looking creature in the tank.  Hubby says its a fresh water shrimp, but he's just hungry.  Where would be good place to see common aquaria bug critters?
(I'm assuming these guys were included at no charge with a plant.)
So far I have found 4 of these things.  If they are a pest or other unwanted creature I want to get them out of there.  But if these things are in any way beneficial - they can stay.

I really can't think of how to describe these things and I don't have a digicam, so I can't put up their picture.  Sorry.  

 

[nonamethefish]

Could it be a gammarus?

 

[pdiddymoose]

What's a gammarus?

 

[equinom]

Nope, not a gammarus - I checked them.  

I'll try to describe:

segmented body - like an insect.
3 pairs of legs, from the center/front part of body
head is sort of a squished/diagonal squarish shape, 2 dark eyes, on sides of head (like a hammerhead shark)
tail is split, like a Y
and I think the mouth was like an algae eaters: turned down

Every time I have found one of these, they have been in the java moss.  As I thin it out and vacuum out the cut off sections - they are in the dirty bucket.  They are not there after vacuuming gravel - only when removing java moss.

I have been searching around the www, and haven't seen anything that looks like these things.  Any ideas?