They are pale, small and have very sharp claws - but the tiny crabs found in local bazaars in Bangladesh are in big demand.
In fact farmers cannot seem to get enough of them.
In the south-west of the country, where swathes of farmland are submerged in salty water, many people have taken up crab farming after struggling to grow rice.
The financial returns are so good that some farmers are contemplating carrying on with crab-farming even if their land becomes suitable for growing rice and other crops one day.
Fattening crabs is becoming the profession of choice for unemployed farmers such as Mujib.
He switched to crab-farming after his land was flooded by a tidal surge which followed Cyclone Aila in May 2009.
"We had to move to temporary shelters on the road because water came into our home," says Mujib, who like many local people uses only one name.
The force of the storm broke the embankments that protected the land from the influx of sea water.
After the storm passed, all Mujib was left with were the remnants of his tiny hut and a small piece of land inundated by salty water.
More than a year-and-a-half later, water still seeps in during high tide and floods acres of farmland, making it unsuitable for growing crops.
"We realised that there was no chance of the water receding anytime soon," says Dr Babar Kabir of the non-governmental organisation Brac, which has been helping with relief and rehabilitation work in the area.
But instead of aid, Brac gave farmers money to buy small crabs, fatten them up and sell them back for export to countries such as Taiwan, Malaysia and Singapore.
Some crabs can grow as heavy as 4kg and fetch up to $5 apiece.
Dr Kabir says the project shows that if land becomes unsuitable to grow crops, it can be used in other ways.
"We tried to move people away from a relief mentality."
And paradoxically in this case, "water gives you a better economic return than land", he told the BBC World Service.
For farmers like Mujib, crab farming has had a clear economic benefit.
"I was able to repair my house with the money I made from selling crabs," he says.
Brac's Dr Kabir also says the environmental impact of crab-farming is limited.
"They feed on small fish, they consume very little and no other chemicals are added," he says.
He believes that farming crabs can be more environmentally friendly than even rice production.
When the embankments are repaired, farmers will be able to flush out polluted water from their lands and prepare for crop production.
The healthy returns from crab farming have also helped overcome a social taboo by encouraging Muslim farmers to take up the practice.
Traditionally it was limited only to members of the minority Hindu community, as many Muslims do not eat crabs for religious reasons and therefore see crab-farming as un-Islamic.
Although crabs and lobsters are not specifically banned like pork, neither are they declared halal like chicken or beef - so most Muslims in Bangladesh just avoid them.
"When your back is to the wall, you know that it's your only income opportunity. So Muslims are also growing crabs," says Dr Kabir.
But many still won't go as far as eating them, he says.