Would a child's (6) baby tooth be soft enough for me to break with my fingernail after its fallen out?

My son came to me with another collection order for the tooth fairy a few days ago.

After going through our ritual of putting the tooth in a small black felt bag under his pillow, to be replaced with hard cash by the tooth fairy, I came to put the tooth away for a keepsake. The tooth had some black fluff stuck to it so I went to scrape it off with my fingernail but found the tooth was very soft, so much so that I could have cut it in half with only the light pressure of my nail.

Is this normal for a baby tooth (none of the previous ones have been like this, though I'm separated from his mother so haven't seen all of them) or have I been swindled by a 6 year old con artist?