A bowl comprising an open top (2), an outer surface (3) and a base (4), in which a plurality of first drainage apertures (5) are provided in said outer surface, in which said base is provided with a resilient bi-stable diaphragm member (6) which is manually switchable between a first dome configuration in which it extends away from said outer surface, and a second dome configuration in which it is everted in relation to said first configuration and overlies said outer surface to close said plurality of first drainage apertures.
