Complex sentence: The extinction does not seem to have been caused directly by human interference; this small limpet disappeared from the fauna because of a sudden catastrophic collapse of the populations of the eelgrass plant, which was its sole habitat and food source.
Split into simpler sentences: The extinction does not seem to have been caused directly by human interference. This small limpet disappeared from the fauna because of a sudden catastrophic collapse of the populations of the eelgrass plant, which was its sole habitat and food source.