User blog comment:Jambellyfatboi/Caribou's Numa Numa no mi/@comment-1908942-20110128020236

The basic ability is that of Mud. So far we now it can absorb things in the fashion of how a Swamp/Bog can suck things into it.

Other powers like using his semi-liquid nature in the fashion of how someone would use Water as a power or hardening it into Clay for blunt attacks are unknown, but possible.

That said, since it seems he can spread himself out, and how most Logias can create their elements with a seemingly infinite power core I was thinking about Franky's barrel, he has Vegapunk Tech now, right? Maybe those metal bars were Seastone. It would explain that a little bit better.