In Dr. Gerald Fagan's lecture series, "Great Battles of the Ancient World", he mentioned that at the battle of Asculum where the Romans squared off against the Epirotes under King Pyrrhus, the Romans introduced a new weapon to counteract the use of war elephants. Dr. Fagan describes these vehicles as anti-elephant wagons. They apparently were enclosed vehicles bristling with spears that contained javelineers.
Wikipedia describes them as "these were ox-led chariots, equipped with long spikes to wound the elephants, pots of fire to scare them, and screening troops who would hurl javelins at the elephants to drive them back."
Dr. Fagan pointed out that they may have been effective if they had been deployed properly. Apparently the Roman commander deployed them on the Roman left so Pyrrhus simply moved his war elephants to the other end of the line.
Since I had never heard of these early "anti-tank" vehicles, I found it all very interesting.