You don't expect seaweeds to flourish in the winter, but Dumontia contorta does. That is, it germinates in the autumn on stones and develops long thin fronds in late winter and early spring. It slowly perishes by the end of May. The only evidence you find of this seaweed in the summer is its base (the holdfast), attached to rocks. It is relatively common in tidal pools in the Wadden Sea and delta region. Its name contorta is related to the fact that the fronds are often twisted (contorted).