What did Mark Zuckerberg do with Synapse?

Could you elaborate on the role that Mark Zuckerberg played with Synapse? Was he an investor, a founder, or simply a user of the platform? What specific actions did he take with Synapse, and how did it impact his later endeavors, such as Facebook? Additionally, was there any notable collaboration or partnership between Zuckerberg and the Synapse team that we should be aware of?