You are bidding for an antique green glass fishing float which were manufactured mainly in Norway and Japan and were used for keeping the fishing nets from trawlers and drifters afloat during the mid 20th C.  I believe that their use has now been largely discontinued.

This particular float came from Small & Co. of Lowestoft in 1965 and has since been used as a licensed bar artefact and garden ornament. The netting has disappeared.  Small & Co. discontinued fishing in the late 60's/early 70's and used their fleet as supply vessels for the North Sea oil rigs.

If you google 'glass fishing floats' there is a lot of information about their history and collectability.