Long Beach, Mass: storm damage unearths submerged grove of mystery roots

Does anybody know the age of the mangrove-like roots that began to surface back in 2012 aside Eagle Rock and the creek? The 2018 winter storm erosion exposed more of a grove line parallel to the seawall. I am curious about the seemingly fossilized piercings and how the landscape may have looked before the beach we walk today.

more photos in my GMG post from 2016: Shore nature challenge: what are these? Long Beach Easter Island

Long Beach Massachustts after winter 2018 storm damage- mangrove like roots surface©c ryan_20180523_134700InkedLong Beach Massachustts after winter 2018 storm damage- mangrove like roots unearthed - detail marked up©c ryan_20180523_134700