First of all, the cell's height should be listed as well.
It doesn't really blow me away and the quantum entanglement brain seems like an unecessary addon unless you want to make it hyper-intelligent. If it tries to escape, why not just drain the cell of water?
As for the twist, I would suggest having it attack any living organism that is between 5-30% of its mass. It then adds the mass of the creature to itself with a significant proportion going to its brain. Add to that the quantum whatnot and you have a hyper intelligent sea spider robot that's getting bigger and smarter as time goes on. Also, have it attack all living things, not just humans.