iOS inexplicably has several camera filters that aren't found in either the Camera or Photos app, but rather in the Messages app. Yes, there are some cool filters that you can only access when you pull up your camera from within Messages. In addition to the normal filters you have when taking a photo with the camera app or adding filters later on while editing in the Photos app, you will find comic book, ink, watercolor, camcorder and aged film filters in the Messages app.
There are a number of artistic reasons to shoot in black and white - it is still seen by some as photography in its purest form as it eliminates the distraction of color, letting the photographer focus on contrast, form, texture and composition. It can also create a mood and give a sense of timelessness to some photos. Whatever your reason, it is easy to take black and white photos with iPhone. You can put a lens filter on before taking the shot so you can see what it will look like, or you can apply it after. Here's how to do it on iPhone:
Ever notice that Hey Siri does not respond when the iPhone is face-down on a table? In fact, this can happen in a pocket, bag, or any situation where the front of the iPhone is covered up. This is a feature of iOS, which shuts off Hey Siri automatically when the iPhone is face-down. Placing the device in this position is the quickest way to disable Hey Siri at any time.