A ground working tool comprising a tubular base body with an inner receiving space for receiving a cylindrical core of solid ground material, connector mechanism for connecting the tubular base body with a rotary drive and locking mechanism for locking the core in the receiving space of the tubular base body. The locking mechanism involves at least one locking unit having a guide rail being disposed at an inner side of the tubular base body and arranged with a deviation angle relative to a tangential direction of the tubular base body and the locking unit further comprises at least one locking element, which is moveably mounted on the guide rail between a radially outer releasing position and a radially inner locking position, in which the core is clamped within the receiving space by means of the at least one locking element.