Neutron ram

From Tardis Wiki, the free Doctor Who reference

The Doctor kept a neutron ram in his TARDIS by the end of his seventh incarnation. The Eighth Doctor asked Grace Holloway for the neutron ram. (TV: Doctor Who)

Behind the scenes

The Neutron ram in the central section, seen right above the screwdriver

Although the neutron ram is not identified on screen, it was identified by REF: The Doctor Who Technical Manual.