What is this???

[StevenC]

On vacation in Vietnam, I was walking through a street market in District 4 of Ho Chi Minh City yesterday when I spotted these things. They have a soft black shell that you can peel open with your fingers (leaving inky black residue on your hands), with a soft nut inside that's like a young Brazil nut.

Does anyone know what these are??

Edited December 24, 2012 by StevenC (log)

[Hassouni]

water caltrops? http://en.wikipedia.org/wiki/Water_caltrop

[Ashen]

that is what I think they are too. water caltrops more specifically trapa bicornis water caltrop http://www.google.ca/search?num=10&hl=en&site=imghp&tbm=isch&source=hp&biw=1243&bih=568&oq=Trapa+natans+&gs_l=img.3..0i24l9.3272.7617.0.8868.6.6.0.0.0.0.130.388.5j1.6.0...0.0...1ac.1.coxpxItcGtU&q=Trapa%20natans&tbo=d#hl=en&tbo=d&site=imghp&tbm=isch&spell=1&q=Trapa+bicornis&sa=X&ei=CiXZUK7pJcaQ0QGIq4DACg&ved=0CFIQvwUoAA&bav=on.2,or.r_gc.r_pw.&bvm=bv.1355534169,d.dmQ&fp=e1b0b7270bdb7f1f&bpcl=40096503&biw=1243&bih=568

[StevenC]

Thank you!!