It's about one-and-one-third times as heavy as an Anchor of a Cruise Ship
In other words, 15,000 kilograms is 1.33 times the weight of an Anchor of a Cruise Ship, and the weight of an Anchor of a Cruise Ship is 0.752 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 11,300 kg. 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 two-and-a-half times as heavy as a Tyrannosaurus rex
In other words, 15,000 kilograms is 2.3 times the weight of a Tyrannosaurus rex, and the weight of a Tyrannosaurus rex is 0.43 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 6,400 kilograms 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 two-and-a-half times as heavy as an Elephant
In other words, 15,000 kilograms is 2.5 times the weight of an Elephant, and the weight of an Elephant is 0.4 times that amount.(for African bush elephant, Loxodonta africana) (Adult, bull)
A bull African bush elephant weighs about 6,100 kg. Among African elephants, both males and females have tusks (whereas female Asian elephants, Elephas maximus, do not have tusks) which can grow to 3 m (10 ft) and typically weigh about 4,000 kg
It's about four times as heavy as a Hippopotamus
In other words, 15,000 kilograms is 3.9 times the weight of a Hippopotamus, and the weight of a Hippopotamus is 0.26 times that amount.(Hippopotamus amphibius) (adult, male)
The average weight of an adult male hippopotamus ranges from 3,000 to 4,500 kg. 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-fifth as heavy as The Space Shuttle
In other words, 15,000 kilograms is 0.21 times the weight of The Space Shuttle, and the weight of The Space Shuttle is 4.8 times that amount.(for Endeavour, a.k.a. OV-105, a.k.a. Orbiter Vehicle-105) (empty weight, excluding main engines)
When empty, the space shuttle Endeavour weighs 71,000 kilograms. The shuttle's spacious cargo bay carried the Chandra X-ray Observatory into orbit in 1999 — a payload that weighed 19,737 kg.
It's about five-and-a-half times as heavy as The Tongue of a Blue Whale
In other words, 15,000 kilograms is 5.6 times the weight of The Tongue of a Blue Whale, and the weight of The Tongue of a Blue Whale is 0.18 times that amount.(Balaenoptera musculus) (adult)
The tongue of a Blue Whale can weigh up to 2,700 kilograms. 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-tenth as heavy as a Blue Whale
In other words, 15,000 kilograms is 0.144 times the weight of a Blue Whale, and the weight of a Blue Whale is 6.94 times that amount.(Balaenoptera musculus)
Blue whales weigh between 73,000 and 136,000 kg. The largest mammal to have ever lived, blue whales feed almost exclusively on krill — tiny invertebrates weighing about 0.001 kilograms each.