What is the unknown orange dot on Apple Watch?

My Apple Watch is showing an orange dot at the centre of the screen at the top. It's not the microphone icon or red unread message icon. it looks like it matches have clock hands inside the icon but no timers or alarms are running. Anyone happen to know what it is? It's recently appeared.

The only recent app I installed I deleted and restarted the watch but the orange dot is still there.