Its an Arrow Crab... It looks like a huge creepy spider! Am I the only one who thinks so?
You can mix any invertebrates that won't consider each other a food source in an aquarium. Mantis Shrimp and Bobbit Worms will attack other invertebrates and fish. Salinity should be between 1.021-1.025 for really any invertebrate.Sharon Sangston Degnan said: