Thanks for posting the additional photo.
Yours is a Pittsburgh area pillar molded decanter from the mid 19th century. It is great to see it retains its original matching stopper. The center of the base shows a typical ground pontil mark - remnants of the pontil scar are still visible and are forming what you see as a whale-shaped figure.
Pillar molded glass in clear is not rare but it is an iconic form American and Pittsburg PA area design.
