Mobstacle: An individual or group of individuals who walk slowly due to focussing on their mobile phone or other mobile device and generally making it difficult for you to pass them, hence you are blocked or slowed down by their nuisance.
Warning - A mobstacle is prone to unexpected changes in direction or erratic gestures, requiring a wide berth by all normal pedestrians.
I missed my bus because I was stuck behind a couple of mobstacles!
Someone or something that bites your ankles.
To a postman, an ankle biter is often known as a dog.
To an adult, an ankle bitermay be a toddler.
To hikers, an ankle biter is sometimes a tick.
And so on.