Do you mean jicama?

It's delicious!! If there are any Latin American markets near you, you'll find it easily. It kind of looks like a large, roundish potato. You have to peel it (rough, brownish skin), but it is usually eaten raw. (Doesn't taste like a potato at all. It's kinda flavorless, but a little on the sweet side. Very crisp and delicious -- goes GREAT with dips, guacamole, etc.) It looks like a potato, but tastes almost like a much less sweet apple. Flavor isn't strong at all, but it's a great crunchy texture and is awesome as part of a crudite of other raw veggies.

Some people make jicama fries...cut in a julienne and bake or fry.

Not sure if there are any Latin markets in Australia. But in the U.S., you can sometimes find jicama at the regular supermarkets in the produce section.

Water chestnuts are the only thing similar that I can think of.

It's a crunchy, starchy root vegetable, similar in texture to raw potato, with an ever so slight sweetness to it.

http://lmgtfy.com/?q=jicama+substitute

A warning, it's a FODMAP veg, so gassy for some. I don't particularly find it all that special - tastes like a cross between raw potato and pear.

What I can't figure out is what it's doing to my skin when I touch it raw. It makes my skin slippery and won't rinse off with water (hydrophobic?). It almost seems to be binding to my fingerprints.

jicama is a tuber that is brown on the outside and white on the inside and has crunchy, mildly sweet flesh it is high in fiber and vitamin C. I love taking slices of it and putting in my lunch box for my paleo safe carb. I suppose you could substitute with any other white, mild flavored tuber for jicama.

Do you have access to kohlrabi? Kholarabi has a similar texture to jicama, although I think that kohlrabi has a more pungent/ intense taste.