Any piece of textile, from clothing to carpet to personal hygiene product is a source of fiber fragment, especially during washing and drying. In the Deheyn lab, we monitor these fragments from different matrices around the world, in air, snow, freshwater from lakes as well as from lagoons and the coastal ocean, down to the deepsea. We also monitor them in animals, from fishes to whales, including humans, with the goal to understand how (and if) fiber fragments enter the foodweb. Such an appraisal of the biology of fiber fragments is presented here to highlight what we know, but especially what we don't know, and where users, industries and policy makers need to focus future research and innovation. The talk will also browse the various challenges in assessing the toxicity of these fiber fragments, as their effect combines physical as well as chemical impairments. An added challenge is related to the diversity of additives used in textiles and the unknown associated with the fate of these additives upon weathering and release in the environment or in organisms by leaching of these additives.