http://wiki.spiralknights.com/File:StrangeSlime.png
At first I thought it was a graphical glitch on one of the blue spiked lichens, but then I realized its core was a skull. Furthermore, items only dropped from it when the skull hit the ground and poofed. Sadly it only dropped crowns and heat, so I don't know what rare item it could potentially drop.
Has anyone ever seen this thing?
Oooh neat. Never seen that one before. The only rare *enemy* I ever get is the gunpuppie that shoots hearts.