Celeriac

Celeriac, also called turnip-rooted celery, celery root, or knob celery, is a variety of celery cultivated for its edible stem or hypocotyl, and shoots. Despite its name, it is not a close relative of the turnip. Celeriac is like a root vegetable except it has a bulbous hypocotyl with many small roots attached.

Storage:

The shelf life of celeriac is approximately six to eight months if stored between 0 °C (32 °F) and 5 °C (41 °F), and not allowed to dry out.[7] However, the vegetable will tend to rot through the centre if the finer stems surrounding the base are left attached. The freshness of the vegetable can be determined by viewing the hollowness of the vegetable; a fresh celeriac should not have a hollow centre.[7] The freshness of the vegetable will also be obvious from the taste; the older the vegetable, the less potent the celery flavour. 

Source:

Bristol market