Large hedgehog

  Large Hedgehogs are among the hardest monsters you will face on the Underwater Tunnel, mainly when you're badly or un-equipped.
  They are small, round greyish monsters that tend to run fairly quick. Unless you can hold them off while fighting other monsters, always try to hunt it down and kill if it runs.
  If you punch them, they may damage your arm, so it's best to attack them with a weapon, even if weak. They also have a nasty tendency for critical bites.