What are some of the general features of radish seeds?

I’m doing a science experiment on the germination of radish seeds, I can’t find anything on the general features, please help me

They are small, brown and hard shelled.

Here is a link with lots of pix http://images.google.com/images?q=radish+seed&ie=utf-8&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&sa=X&oi=image_result_group&resnum=1&ct=title

go to a health food store and you can see […]