Academy researcher Rich Mooi talks about sea urchins and sand dollars and why many sand dollars have holes.

The California Academy of Sciences is the only place in the world with an aquarium, planetarium, natural history museum, and fourstory rainforest all under one roof. Visit us online to learn more and to get tickets: http://www.calacademy.org.

Connect with us!
• Like us on Facebook: http://bit.ly/CASonFB
• Follow us on Twitter: http://bit.ly/CASonTwitter
• Add us on Google+: http://bit.ly/CASonGoogle