It could be a crawdad, a crayfish, or a scorpion. The best thing to do would be to enter all these insects into a search engine, like Google, and determine which one it resembles best.
If the bug is a dark color, and has little pincher looking things on its back end- it is an earwig. The scientific name is called the Dermaptera. They don't carry disease.
This sounds like a scorpion. If it's tail is curved up then keep away, they are very poisonous and dangerous. Call an exterminator and don't touch those bugs.
