interesting creature id?

[zeddy]

last night i was looking in my tank when the lights whent off and found the coolest looking thing. i couldnt get a pic because it was dark and the flash kept giving a reflection. so it was alot like a seahare or a slug/nudi looking thing, but it is a tan color body the neat part is the row of bright blue dimond shaped spots down its back. it was in a hole in my rock and worked his way inside it and i havent been able to see it again if anyone has an idea what this is would be great because i would like to see it in a photo