So I was doing my own thing several weeks ago, before the update and having no beta access. I was in the mine mining and killing monsters in a new save file to complete the monster goals in the Guild. While blowing up stuff with bombs a creature I have never seen before popped out of the rocks (I guess?) and started to run away, I didn't know what it was capable of so I hit it and killed it. I didn't come into my mind to take a screenshot of it and after the encounter I browsed the web to see what it might be and what drop it may have since it dropped nothing. No results, whatsoever. Again, note that this was about 3 weeks ago. Before the new update and with no beta access. That doesn't really mean much to be honest, because not even the changelog shows anything like the thing I saw. Three weeks forward I am still playing and even forgot about the find, giving it no further thought after telling myself: "If I found it once, I can do it again. Whatever I actually did, because I don't know. I guess I'll randomly stumble upon it another time." Right before writing this post I found it again and my first reaction was to hit that PrtSc button like it was never hit before and here it is: This time I didn't hit it and tried approaching it, to see if it deals damage. It does not. It ran into that corner and started shaking. That's all I have. If anyone knows anything, please share.
Please correct me if I'm wrong, anyone, but I believe it is the Rock Crab without a rock on its back. You said you were using bombs - they can destroy the rocks the crabs carry and leave them "naked". That's why it ran away.
This is the answer. That's a rock crab without its rock. You can either hit a rock crab with a pickaxe a few times and break it or use bombs. Once rock-less, it will scurry away from you. Good thing is that you can sometimes get a Crab drop from them, which is useful in completing the Crab Pot bundle.
Oh, it all makes sense. I was too absorbed by the fact that after 500 hours of playtime I have found something I have not seen before. I rarely use bombs and I doubt I would have ever tried to pickaxe the crab several times to see what happens. The wiki even mentions this but I bet it's everyone's fault for not getting full info on weaker enemies they only meet few times in lower level mine rooms. =p Thank you for the answers.
