http://www.english-heritage.or[...]_Hill_Finds_Update_Week_05.pdf

"Pieces of antler pick are the next most prevalent artefact to be recovered from Silbury Hill so far. The example on the left exhibits old breaks and as you can see is remarkably well preserved. Antlers were ideal material for the breaking up of the chalk used to construct the mound,and are often found in association with prehistoric ditch structures."