I thought they were stylised roses especially when drawn with stylised leaves around them.Aren't they used in the 4 moolai Kolams and on the padis and corners?
Yes, they are used in the corners and in borders a lot, but they're not roses, as far as I know :)
This looks very similar to the symbol of Sicily, the island where I live.
http://en.wikipedia.org/wiki/Triskelion