Well never fear, my friend: I don't think Plato ever thought that his theory would in any way consign you, a human being, to the status of "a giant sponge."
Plato is not a Buddhist. I don't even think the Buddhists would consign you to such a status in nature. But then, I am only a very general reader in Buddhist philosophy, being fully engaged by the Christian one -- and more than that, in its eschatology.
Whatever the case, I strongly doubt that Plato was a pantheist.
Which slant?