Willow and Jaden Smith – the son and daughter of Hollywood A-listers Will and Jada — have signed on as Youth Ambassadors for Project Zambi, a charity aimed at raising awareness and money for orphans who have lost their parents to the AIDS epidemic in Africa.

A Project Zambi celebrity charity auction on eBay kicked off Tuesday, featuring decorative elephants signed by stars like George Clooney, Scarlett Johansson, and Alicia Keys.

“Willow and I joined Project Zambi to represent all the kids out there who want to make the world a better place. We want to encourage kids everywhere to lend a hand and join us in spreading the word about how much children who have been orphaned by AIDS in Africa need our help,” Jaden says.

The 10-day online auction ends Oct. 15.