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Well done, Lynne Spears!  Brit’s mom showed off a killer figure in an age-appropriate black bathing suit while swimming with her grandkids in Dallas, Texas.  Whatever the hell this 56-year-old show-stopper is doing – be it working out with Britney’s dancers or a couple of laps around the high school track – it’s working.

PHOTOS: Lynne Spears Chats On Her Celly Piece

Grandma Spears (this title doesn’t fit) splashed around with Jayden, Sean and Maddie (Jamie Lynn‘s daughter) while B. Spears continues her Femme Fatale tour, which BTW, has been getting rave reviews.  Holla atcha pop princess and her MILF-tastic mama.