This is a surprisingly common problem! The tree was grown too close to the coast and was affected by the constant motion of the waves which ultimately had an effect on the growth of the tree in it's formative years, it is a phenomenom 'officially' known as
imitatus wavicus. The person that sold you this piece of 'crap' timber certainly saw you coming and off-loaded it the first chance they got, I hope you didn't pay too much for it.
There is no fix for this sorry piece of tree wood so if I was you I would remove it with an axe pronto and buy a decent piece with perfectly straight grain &
definitely no grain peculiarities. This piece could
possibly be used as kindling as long as all traces of finish are removed prior to setting light to it or maybe be a part of a driftwood sculpture in the back yard
