It's scary science fun!Your child will love this amazing alternative energy science kit! Your future scientist will build the entire body of the spider (over 30 parts!), put the gears together, and activate the fuel cell module with a saltwater mixture. The magnesium metal sheet (3 sheets included) can operate the Spider for about 5-7 minutes, continuously. The Salt Water Fuel Cell Giant Arachnoid Kit is a great way to learn about new forms of clean energy, while building and powering a super cool and freaky science toy - feed it saltwater and watch it scurry away!