That sort of material behavior occurs in real life under rare circumstances.
Corn starch, water, and one or two other ingredients, when combined in the right proportions, will instantly (but temporarily) harden when hit with high force, but otherwise allow your hand to easily move through the substance if not at a high attack speed.
I had the opportunity to witness this at an event at a university engineering campus.
Materials
• 1 cup of water
• 1 to 2 cups of cornstarch
• Mixing bowl
• Food coloring (optional)
Silly Putty behaves the same way. I need a new egg full!
8^)