Can the traffic flows well without NAT?

Hello, I'm so shocked because I just saw the weird situation.

First of all, plz see the below catured picture.

To sum up,

1. I configured HA configuration between SSG-140 deivces.

2. I configured IP configuration on SSG at Trust(10.0.0.1) and Untrust(192.168.10.80)

3. I permitted the policies (http, https, dns, ping) from Trust to Untrust.

That's all, and then I did ping 8.8.8.8 at PC, but it flows very well.

                                           ping 192.168.10.1

I don't think it flows well because I don't configure at SSG to configure NAT! (eg.VIP, DIP, MIP)

I just configured IP and policies.

Even though I permitted PING policy, I don't know why it flows well without NAT.

Anybody knows its fundamentals?

Regards,