Mercmes, codenamed UB - 07 Quicksilver, is a steel poison ultra beast.
The ultra beast resembles a mass of sentient metallic goo. It has pupil-less yellow eyes, it appears to be hunchbacked, and seems to consist of only a head and finger-less arms. It appears to be constantly melting. It has flat, penguin-like arms.
Mercmes is known to be fast on the ground and emit a poisonous toxin.