Cocoyam is a Taro plant, or Elephant Ear, Arecacae.
Yams are vining plants,
The cooked tubers look a bit more like Yams to me, but it is hard to tell.
Uncooked Taro skin has growth rings visible, and usually a stem area on one end, like a carrot.
Yams usually have brown woody looking skin, often with filaments or hairs, no stem area on one end.
Another possibility is Cassava, which looks like a pointy Yam, but with a stem on one end ( unless cut off before sale ).
Pretty sure it is not a Sweet Potato.
This answer reminds me of aa Xmas in Tropical Australia, baked Taro, Yams, Potato, Pumpkin in a cast iron oven, over a campfire.