In the Festschrift for 1200-year celebration of the village Olnhausen is found the following statement concerning the family crest:
In the local coat of arms and family coat of arms of Olnhausen a man holds an eel (german: Aal) in his right hand, and in the shield there is a fish trap. From these symbols could be deduced the name Aalhausen, since there are plenty of eels in the river Jagst. A dialect synonym to Eel is also Ohl, and in old records and documents you will find in many cases the diction Ohlhusen or Ohlhausen.
Nevertheless, the author tends to believe that a Franconian clan leader named Ollan, is to be regarded as the eponym of our village. At the time of origin of the village this kind of naming was common. In the deed of donotation to the monastery of Lorsch is mentioned „ad ollanhusen“ which means the house of Ollan. [..]
Still in 1278 the name appears in documents as „Ollinhusen“, which undoubtedly corresponds to the name „Ollanhusen“. A conceivable development could be therefore: Ollanhusen – Ollinhusen – Ohlhusen – Ohlhausen – Olnhausen.
text source of german article: Hans Hain. Aus der Vergangenheit des Dorfes Olnhausen. Mit Beiträgen von H. von Olnhausen und R. Arzt. Published by the municipality Jagsthausen-Olnhausen on the occasion of the 1200-year celebration in May 1981