starfish

Sorry if this is the wrong place to post but I didn't see any top lines subjects that seemed to fit. Any chance I can get some help identifying this snail and starfish? Thanks!!!

 I have no idea what I'm doing. I got a free 30 gallon tank from some weird lady off of craigslist. It has 2 cracks on one side of it that I plain to seal up with silicone despite the fact that it does not leak. (i've tested it in my bathtub). Where do I get salt water? how does this work? I...