Carved ivory tusk from the Loango Coast - 19th - early 20th century

The item in question is a carved elephant tusk that I believe was done by in the 19th or early 20th Century. All I have been able to find on my own is that Kongo carvers based around the mouth of the Congo River along the Loango Coast made many ivory objects to sell to Europeans. Most impressive are the carved ivory tusks and I believe this is one of those tusks.  It is over 30 inches in length and the full length has been carved in a spiral denoting animals, native peoples (some showing cannibalism?) and missionaries.  I think it may convey the history of the region. The tip of the tusk is covered with a 3 inch cap of silver (stamped "sterling").