I refer to some posts of our dear friend Matchlock posted in March 2014 here
http://www.vikingsword.com/vb/showpo...9&postcount=68
In 1983, a heard of several hundred ceramic grenades was discovered next to the New Castle at Ingolstadt, Germany, during construction work for an underground car park.
Since 2014 my wife and myself are involved in the investigation of the find in cooperation with Stadtmuseum Ingolstadt. Hereafter you will find our first introduction and intermediate report on our findings in German language:
https://www.academia.edu/31775145/Ex...aus_Ingolstadt
And here you will find an English and French abstract of our report:
https://www.academia.edu/35146728/Fr..._Abstract_2016
Also on my private homepage you will find an updated summary
https://www.franzkowiak.de/index.php...-grenades.html