Android XML shape - Draw inward curves?

Question

I'm trying to create shapes that look like talk bubbles. I've already created the bubble, but I'm trying to create the "tail" of the bubble in XML as well.

I had an idea that I could make ovals that hide an rectangle underneath them, but I doubt that it is possible.

How do I create this "tail" shape?

This is just an ordinary triangle I've made:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item>
        <rotate
            android:fromDegrees="45"
            android:toDegrees="45"
            android:pivotX="0%"
            android:pivotY="0%"
            >
            <shape
                android:shape="rectangle"
                >
                <solid
                    android:color="@color/white" />
            </shape>
        </rotate>
    </item>
</layer-list>