It depends on what you're comparing them too...
On Moe's scale of hardness, a fingernail is roughly 2.
Nails (and finger nails) have volume.
Finger nails are made of a protein called keratin.
No one invented finger nails.
Actually, finger nails contain protein (called "keratin").
By system, you mean category.. I'm not sure if you mean finger nails or like tool nails, so I'll give you both. Finger nails: Body parts Tool nails: Hardware
Nails are typically made of metal, such as iron or steel, because these materials provide strength and durability for construction purposes. Plastic is not commonly used for nails as it is not as strong or reliable for holding materials together.
Finger nails (and toe nails) are made of keratin.
Nails
yes
yes
I believe they grow faster.
Yes, it is like our finger nails