I had this rock setting towards the back of my tank and I noticed slowly over time that a mound of chunky sand started to get bigger and bigger behind it. I finally pulled the rock up to take a look at what was going on back there and I found this worm. Half of it is burrowed into The Rock the other half was out flailing around. The body of the worm is about 3/16" to 1/4" in diameter. What the heck is it?
