Campylopus introflexus (Heath star-moss)
Campylopus introflexus is a primary colonist capable of smothering large areas of bare ground, so I guess it must have an impact as an alien. But I'm not aware of any meaningful studies that have been undertaken to measure its affects on native bryophyte biodiversity. I love the way the capsules are buried in the leaves (again like other Campylopus species) and the fascinating movement of its hairpoints - when plants dry out you can watch it happening. I presume the deflexed hair points help to decrease the short-wave radiation load in hot weather. Who knows. Just because we can now land a fridge on a comet 350 million miles away, we shouldn't stop asking these little mossy questions.