Mystery blue microphone icon

Recently, perhaps after the latest update to 13.2.3, or after linking up bluetooth in our new Honda, my iphone 6plus began typing out any works I speak when the message function is used. It takes dictation but the dictation function is off. We note the presence of a small blue microphone icon in the upper right corner on the home screen and all others. It is immediately adjacent to the location icon.

What is this blue icon of a microphone and how do we stop the dictation function on imessage?