Even though I suggested a plastic product, I can say that I have noticed that my ray does show interest in the metal tongs we use for blackworms. I fed it a nightcrawler for the first time a couple of days ago, and it didn't recognize it as food...I just dropped it in instead of using the tongs. As soon as I stuck the tongs in to remove the worm, he rushed over and gobbled the nightcrawler up.
I am not exaggerating, and I am unbiased...The only reason we use metal tongs is because the plastic ones are too weak to grab hold of the blackworms.