It's about one-seven-hundredth as heavy as a Rhinoceros
In other words, 0.00000000290 megatonnes is 0.0014 times the weight of a Rhinoceros, and the weight of a Rhinoceros is 710 times that amount.(for Black rhinoceros, Diceros bicornis) (Adult, male)
An adult black rhinoceros weighs between 0.00000210 megatonnes. Rhinoceros are extremely aggressive — nearly one of every two males will die as a result of fighting with other rhinoceros.
It's about one-nine-hundredth as heavy as The Tongue of a Blue Whale
In other words, 0.00000000290 megatonnes is 0.0011 times the weight of The Tongue of a Blue Whale, and the weight of The Tongue of a Blue Whale is 910 times that amount.(Balaenoptera musculus) (adult)
The tongue of a Blue Whale can weigh up to 0.00000270 megatonnes. 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 1,000 times as heavy as a Penny
In other words, 0.00000000290 megatonnes is 1,200 times the weight of a Penny, and the weight of a Penny is 0.00083 times that amount.(United States) (formally one-cent coin) (Union shield design, 2010-present)
The weight of a United States penny is 0.00000000000250 megatonnes. According to a 2010 report by the United States Mint, the cost of manufacturing and distributing a penny is $0.0179 — more than its face-value.
It's about one-one-thousand-five-hundredth as heavy as a Hippopotamus
In other words, 0.00000000290 megatonnes is 0.000773 times the weight of a Hippopotamus, and the weight of a Hippopotamus is 1,290 times that amount.(Hippopotamus amphibius) (adult, male)
The average weight of an adult male hippopotamus ranges from 0.000003750 megatonnes. 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 1,500 times as heavy as a Playing Card
In other words, the weight of a Playing Card is 0.00063 times 0.00000000290 megatonnes.(ISO 216 B8 size, 2.5" x 3.5")
A single ISO 216 B8-size playing card weighs 0.00000000000180 megatonnes. Although this size is the most common home playing card, many casinos use "bridge size" cards — 2,640 sq. mm (4.036 sq. in) smaller in area.
It's about one-two-thousandth as heavy as an Elephant
In other words, 0.00000000290 megatonnes is 0.00048 times the weight of an Elephant, and the weight of an Elephant is 2,100 times that amount.(for African bush elephant, Loxodonta africana) (Adult, bull)
A bull African bush elephant weighs about 0.00000610 megatonnes. 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 0.00000400 megatonnes
It's about 2,000 times as heavy as a Paper Clip
In other words, 0.00000000290 megatonnes is 2,100 times the weight of a Paper Clip, and the weight of a Paper Clip is 0.00048 times that amount.(average)
Notwithstanding the tremendous variation in sizes and materials, a typical paperclip weighs about 0.00000000000140 megatonnes. The country of Norway has used the paper clip as something of a national symbol since the end of World War II based on the erroneous notion that the paperclip was invented by a Norwegian, Johan Vaaler. However, the paperclip had already been in existence for at least 30 years by the time of Vaaler patented his paperclip design.