Naturdenkmal Schneckenreservat, Bad Vöslau

The natural monument Hansybach also called Hörmbach or Hirmbach is a small stream reserve in Bad Vöslau in Lower Austria, where three species of water snails are to be protected. This natural monument is one of 13 in the municipality's territory. It is located on municipally owned land and has been generously restored by the municipality. In 1979, an information pavilion was added to the natural monument.

The water snails living here have survived since the Tertiary period and are found nowhere else in the world except in the nearby thermal spa. They live in the natural monument in a small stream, which is kept at the constant temperature of about 24 °C all year round by a thermal spring.

Due to the consistently warm water, the stream was used as a laundry sink until the 20th century, at times when there were no washing machines. However, since the stream has a relatively high flow rate of 20 l/s, the snails were not affected by the detergent contamination. The snail species living here were discovered by the head of the mollusc collection at the Natural History Museum in Vienna, Oliver E. Paget, who also initiated the protection of the species.

In its further course, the Hansybach also passes under the Wiener Neustädter Kanal and the Thermenradweg in the east of Bad Vöslau and flows into the Schwechat in Tribuswinkel.

The unique reserve, which has so far been used mainly for scientific purposes, is also to be used more for tourism in the future.