Daymen's rock

Full Item Description
Daymen's rock is simply a small rock, the size of a fist. It looks like a normal rock. When angry, it appears to crack along a jagged line that almost bisects it down the middle, and uses the jagged edges as teeth.

History
The luckless wizard Daymen Scarb tried many things in an attempt to find some form of magic he was good at. This was the first and last time he ever enchanted something.
Trying to simply enchant a rock to glow, possibly the easiest enchantment to do, he found that like with all his other magic it simply didn't work right. At first, it did glow, though rather dimly. Then it exploded into a stony maw, which proceeded to chase Daymen around for the better part of a half hour. After it seemed to grow bored of that, it returned to looking like a normal rock, and calmly rolled out the door.

Magic/Cursed Properties
The rock seems to be somewhat sentient. That is to say, if it notices something moving (which isn't always, rocks have notoriously poor eyesight) it bursts into a rocky maw and tries to bite it with extreme prejudice. It moves in two ways, depending on if it's in mouth form or not. If it isn't, it simply rolls along the ground, as though down a gentle slope. When it is a maw, it moves in leaps by opening itself quickly, generally chomping at the apex of its jump.
Though occasionally docile, the best way to get a reaction out of it is simply to hit it with a stick or, if you're brave enough to pick it up, throw it at whatever you want it to attack. It's about as smart as a rock, so it doesn't realize that someone threw it. As far as it knows, it hit something, so that something is going to get a faceful of rocky teeth.