Sodium Alginate Halloween Eyeballs #HalloweenScience #Chemistry In this fun science activity, you can make edible “eyeballs” using sodium alginate, calcium salt solution, and food coloring. Sodium alginate, a natural polymer from seaweed, forms a gel when it comes into contact with calcium ions. When you drop a sodium alginate mixture (with food coloring for effect) into a calcium chloride solution, the calcium ions cause the alginate to cross-link, creating a squishy gel-like skin around the li