Thai Micro Crabs are also known as "false spider crabs," and their scientific name is Limnopilos naiyanetr.  These are tiny, fully aquatic crabs that so far have only been found in one specific river in Thailand.  They are a very new and rare addition to the aquarium hobby, making them extremely difficult to find in pet stores or even online.  This is one of the very few types of crab that can live fully immersed in water at all times, so they are able to be kept in any freshwater aquarium.