Complex sentence: Abandoned mucus houses sink to the deep, collecting organic particles during their descent, and form an important contribution to marine snow, since "Oikopleura" is abundant and it is a very active filterer, using powerful strokes of its tail.
Split into simpler sentences: Abandoned mucus houses sink to the deep, collecting organic particles during their descent. They make an important contribution to marine snow, since "Oikopleura" is abundant and is a very active filterer, using powerful strokes of its tail.