I got a tad late to the battle, and found this: http://wiki.spiralknights.com/images/6/60/Turtle.jpg
Knew it was a tortodrone from the area and circles on the ground. And luckily it was always on fire or shocked so I could see it. Still it was pretty odd. Maybe had to do with the monster being on fire when I reached the screen? Or something tortodrone specific.
Also, please make images save as max quality jpgs. This screenshot was 2mb as png and wouldn't let me upload, and there's no visible difference with the jpg 1mb version.
I've noticed this too, and bugged it at the time. I thought it was due to the tortodrone being already enraged before I joined the party.
Also, 1mb for a screenshot? You don't need max quality for uploading, drop it to 80 or so and get a 100kb file that looks the same.