They look like 4th Century A.D. bronze coins.
They don’t look like they were just pulled out of the water
My brother, who is not a coin collector, forwarded me this article and likewise expressed extreme doubt that bronze coins would come up from 1700 years under salt water looking like this.
From the depths of the Black Sea, covered in anoxic mud, might be believable. But these were found off Sardinia, and the pictures of the recovery show the site in bright sunlight- so they were found in quite shallow water.
I'd expect a pile of bronze coins under such circumstances to come up out of the ocean looking like a fused lump of malachite.