It's about as heavy as The Tongue of a Blue Whale.
(Balaenoptera musculus) (adult)
The tongue of a Blue Whale can weigh up to 66 firkins. Despite their tremendous size, blue whales feed almost exclusively on tiny crustaceans called krill and cannot swallow anything much larger than a beach ball.
It's about one-and-one-tenth times as heavy as a Giraffe.
It's about one-and-three-tenths times as heavy as a Rhinoceros.
In other words, the weight of a Rhinoceros is 0.77 times 66 firkins.(for Black rhinoceros, Diceros bicornis) (Adult, male)
An adult black rhinoceros weighs between 51 firkins. Rhinoceros are extremely aggressive — nearly one of every two males will die as a result of fighting with other rhinoceros.
It's about seven-tenths as heavy as a Hippopotamus.
In other words, 66 firkins is 0.718 times the weight of a Hippopotamus, and the weight of a Hippopotamus is 1.39 times that amount.(Hippopotamus amphibius) (adult, male)
The average weight of an adult male hippopotamus ranges from 91.9 firkins. Appearances to the contrary, adult hippos cannot swim or float in water; they actually move by leaping and walking across lake bottoms at about 8 kph (5 mph).
It's about one-and-three-fifths times as heavy as a Car.
In other words, 66 firkins is 1.631 times the weight of a Car, and the weight of a Car is 0.6131 times that amount.(for 2009 Ford Taurus; automatic transmission; curb weight)
A 2009 Ford Taurus weighs 40.47 firkins. The first mass-produced car, the Curved Dash Oldsmobile — introduced in 1901 — weighed just 9.455 firkins.
It's about two-fifths as heavy as a Tyrannosaurus rex.
In other words, 66 firkins is 0.42 times the weight of a Tyrannosaurus rex, and the weight of a Tyrannosaurus rex is 2.4 times that amount.(for FMNH PR2081, a.k.a. "Sue") (a.k.a. Tyrannosaurus, a.k.a. T-Rex) (estimated live weight)
The notable Tyrannosaurus specimen housed at the Field Museum of Natural History in Chicago, Illinois, "Sue," is estimated to have weighed about 160 firkins while alive. A renowned predator in popular culture, the teeth of tyrannosaurus rex were up to 33.02 cm (13 in) long.
It's about one-third as heavy as an Elephant.
In other words, 66 firkins is 0.3586 times the weight of an Elephant, and the weight of an Elephant is 2.789 times that amount.(for African bush elephant, Loxodonta africana) (Adult, bull)
A bull African bush elephant weighs between 184.1 firkins. Among African elephants, both males and females have tusks (female Asian elephants lack tusks) which can grow to 3 m (10 ft) and weigh up to 2.205 firkins.