"They make every effort not to be eaten," Alex Stollznow from Sydney Fish Market tells SBS Food.
However, inside the ball of long, pointy spines are sweet, creamy, delicate roe, considered a prized delicacy in many parts of the world.
Mr Stollznow, a fish expert and a tour guide at the Sydney Fish Markets, remembers his first taste of sea urchin as a "unique seafood experience".
"Nothing I know from the ocean is as creamy and sweet while still being briny as sea urchin."
What are sea urchins?
Source: Sydney Fish Markets
Sea urchins are marine invertebrates classified in the Echinoidea family. They exist in all parts of the world, with roughly 950 species inhibiting every ocean depth. Only around 18 of the species are edible.
In Australia, three species of sea urchins, purple, red and green/white, are harvested, with the purple making up most of the commercial catch, says Mr Stollznow.
When you crack open the spikey shell, you'll see five "tongues" of roe, the edible part of the urchin, the sex organ or gonads.
The roe, also called uni (oo-nee) in Japanese, can vary in colour from off-white to a vivid ochre, depending on its environment and the kelp they eat.
While the rest of the world is beginning to discover this ocean’s treasures, Japan has long harvested them, making them the largest consumer of uni. They are most commonly harvested from the waters around Hokkaido, the Northern part of Japan, although they also import from countries such as Australia.
Urchins may seem to be all year round, but only five varieties are harvested around Japan to be eaten, all with their particular season. The Ezo-bafun urchin, for example, known for its larger size and richer, sweeter taste is only harvested between July and September. Because it's most commonly eaten raw, as sushi or uni-don, the fresh in-season urchin can become very expensive.
In Tokyo last year, 1kg of uni averaged 24,121 yen or approximately AU$270.
Pest or delicacy?
"Although native to New South Wales, purple urchins are now dangerously in overabundance in many places, including Victoria and Tasmania," says Mr Stollznow.
Climate change and the warming waters have caused the urchins to proliferate, decimating the kelp forest, which is crucial to the ecosystem. Currently, the government pays for culling, but "we recommend consumption," he says.
Although the sea urchin population is exploding, whether they are marketable is another question. Only the roe from healthy urchins, those that have eaten good kelp, are marketable, and the labour that goes into harvesting and processing can add on the dollars.
How do you eat them?
How you eat them will depend on the type of urchin.
Nobuyuki Ura of Ora Restaurant Sydney says when using urchins from Australia for sushi, he only serves urchins harvested in Tasmania.
Harvested in the colder waters, Tasmanian urchins are rich in sweetness and creaminess, making them comparable to the Hokkaido urchins of Japan, he says.
"These are only available mid-winter, but I want the customers to enjoy its deliciousness and rarity."
The purple urchin readily available at the markets has a "touch of bitterness" compared to these Tasmanian urchins, says Mr Ura.
"These are great when cooked, served in dishes like the pasta."
Mr Stollznow says pasta is a great way to introduce urchins to people who have never tasted urchins.
"It is incredibly simple to make. Cook garlic, onion, and butter, then add a few tongues of roe. Urchin's unique fragrance and creaminess make them a pure seafood carbonara."
In Japan, apart from sushi and pasta, uni can be eaten as chawanmushi (savoury egg custard) or as part of a topping or canapé.
The Sydney Fish Markets recently hosted Australia's first sea urchin competition to shed light on the species ignored till now. Chefs from various cultural backgrounds gathered to cook with urchins.
Source: SBS
"Crumpets, custards, pasta, even cheesecake. There is no wrong!"
The interest in urchins is on the rise, with the Sydney Fish Markets introducing Urchin Uncovered cooking class just last year, and is proving to be very popular.
Australia’s first sea urchin competition held in 2022 Source: Sydney Fish Markets
Purchasing and storing urchin
The most cost-effective way to purchase sea urchins is as a live whole, setting you around $5 to $8 per pop.
If you are not quite ready to open the urchin on your own, there are many pre-proceed roes in the market. Some may come in brine, others in dry punnets. The premium uni exported to Japan come in wooden boxes, which could set you at hundreds.
Although the quality and yield may decline, you can also harvest on your own. In New South Wales, there is a limit of ten sea urchins per person per day.
If you have a whole live urchin, it is best to be cleaned that day and stored on a damp paper towel.
Mr Ura says when serving raw, uni can be stored in a refrigerator (below 3 degrees) for up to 4 days. Freezing is not recommended as it will lose both texture and flavour.
