Mystery fruit / seed pod

Mystery fruit / seed pod

071020_08delaware
From yesterday's walk along the Delaware River out behind the Philadelphia International Airport. There were lots of these seeds along the shore at the high water mark, and this one fruit/seedpod that appears to have been stepped on to make it pop. Seedpod was about 3" long. I never saw anything like it before in my life. This location is about 2 miles south of the Port of Philadelphia, so it's possible that a carton of some exotic foodstuff fell into the river. Anyone recognize this thing? I thought about collecting a few of the seeds and planting them, but Roy says I have enough horticultural experiments going on right now. ETA: Please pass this along to anyone who might have an idea what this thing is.
View from the couch

View from the couch

squirrels

squirrels

Bamboo

Bamboo

ID’s

ID’s

Things I have learned – this gardening season

Things I have learned – this gardening season

New room.

New room.