MARKS & Spencer has launched legal action against Aldi over the discounter's copycat version of its Colin the Caterpillar cake.
The posh supermarket is arguing the similarity of Aldi's Cuthbert the Caterpillar cake leads customers to believe they're of the same standard.
The trademark infringement claim, lodged with the High Court this week, also claims it "rides on the coat-tails" of M&S' reputation with the product.
Aldi launched its caterpillar cake in 2019 for £4.99, while M&S charges a pricier £7.
M&S now wants Aldi to remove the product from sale and agree not to sell anything similar in the future.
It launched Colin the Caterpillar around 30 years ago and the design has been largely unchanged since 2004.
The only exception is during seasonal events such as Halloween, Christmas and Easter, when M&S launches temporary new designs.
Just like Colin, Cuthbert is made with a chocolate sponge cake filled with chocolate buttercream - and it also comes with a white chocolate face.
It's not available on Aldi's website though, and the discounter is yet to confirm whether it's available in all stores.
M&S has three trademarks relating to Colin, which the retailer believes means Colin has distinctive character and reputation.
An M&S spokesperson said: "We know the M&S brand is special to our customers and they expect only the very best from us, love and care goes into every M&S product on our shelves.
"So we want to protect Colin, Connie and our reputation for freshness, quality, innovation and value."
The Sun has contacted Aldi for comment.
The discounter is well-known for its copycat products, which also include other treats such as chocolate and cookies.
However, a few years ago, it faced legal action from small businesses which claimed the supermarket was ripping off its goods.
In 2019, Charlotte Tilbury also won a legal battle against Aldi after the discounter sold £6.99 copycat dupes of its £49 bronzer.
SUN SAVERSHave your cake jar and eat it with our top tips on the new sweet trend
AUCTION STATIONSHouse in Wales on sale for just £12,000 - but wait until you see inside
GAS-LIGHTEDHundreds of British Gas engineers left furious after losing their jobs
RETAIL WOESAsda to axe 1,200 jobs at its bakeries under major restructuring plans
NO CREDITHalf a million on Universal Credit have had benefits cut by surprise tax bill
NOT FINEMartin Lewis warns drivers should check photo licences NOW or risk £1,000 fine
Last month, a home baker was mercilessly mocked for a DIY version of the Colin the Caterpillar cake with Brits claiming it gave them "nightmares".
Meanwhile, M&S rolled out a new Easter Colin the Caterpillar cake this year.
It came after shoppers were "disturbed" by the Easter version last year, claiming it looked "demonic".