Oracle Text

Ferropede can't be blocked.

Whenever Ferropede deals combat damage to a player, you may remove a counter from target permanent.

Card Rulings

12/1/2004 Any permanent is a legal target for Ferropede’s last ability, not just one with a counter on it.
12/1/2004 If there’s more than one type of counter on the targeted permanent, Ferropede’s controller chooses which counter to remove from it.