It's about three-tenths as heavy as a Tyrannosaurus rex
In other words, 31,000,000 grains is 0.310 times the weight of a Tyrannosaurus rex, and the weight of a Tyrannosaurus rex is 3.20 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 99,000,000 grains 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 four times as heavy as a Grizzly Bear
In other words, 31,000,000 grains is 3.860 times the weight of a Grizzly Bear, and the weight of a Grizzly Bear is 0.2590 times that amount.(a.k.a. brown bear, a.k.a. silver bear, Ursus arctos horribilis) (Adult, male, coastal area population average)
An adult, male grizzly bear from a coastal area (where food is plentiful) can weigh up to 8,040,000 grains. In spite of their tremendous size, grizzly bears can run at speeds of up to 55 kph (34 mph).
It's about four times as heavy as a Polar Bear
In other words, 31,000,000 grains is 3.890 times the weight of a Polar Bear, and the weight of a Polar Bear is 0.2570 times that amount.(Ursus maritimus) (adult, male)
An adult, male polar bear weighs between 7,960,000 grains. Polar bears are so heavily insulated by their 9.9 cm (3.9 in) layer of blubber that they are often difficult to detect using infrared photography sensors.
It's about four-and-a-half times as heavy as a Grand Piano
It's about five times as heavy as a Horse
In other words, 31,000,000 grains is 4.80 times the weight of a Horse, and the weight of a Horse is 0.210 times that amount.(Equus ferus caballus) (Arabian, adult)
n Arabian riding horse (or similar breed) weighs between 6,500,000 grains. During races, horses must carry jockeys and their equipment, which in the Kentucky Derby, for example, can weigh up to 840,000 grains.
It's about one-fifth as heavy as an Anchor of a Cruise Ship
In other words, 31,000,000 grains is 0.1780 times the weight of an Anchor of a Cruise Ship, and the weight of an Anchor of a Cruise Ship is 5.620 times that amount.(for QE2 forward anchor, a.k.a. RMS Queen Elizabeth 2)
Each of the forward anchors of the RMS Queen Elizabeth 2 weighs 174,000,000 grains. The anchor of the QE2 now sits in front of the Holyrood Church in Southampton, England, United Kingdom, along a pedestrian tourist route known as "the QE2 mile."
It's about eight times as heavy as a Pig
In other words, the weight of a Pig is 0.130 times 31,000,000 grains.(Domestic pig, Sus scrofa domesticus, a.k.a. S. domesticus) (adult)
Domestic pigs weigh between 3,900,000 grains. The titular character "Babe the pig" in the 1995 family film was played by 48 different American Yorkshire piglets due to the length of filming and the rate at which piglets reach adulthood.