The start-up known around Silicon Valley for its comfy slip-on sneakers is hoping to take over another part of your closet.Allbirds is venturing further into the clothing category, debuting four new items Tuesday: A T-shirt made out of discarded crab shells; a wool cardigan; a wool jumper (a Briticism for a pullover sweater); and a wool puffer-jacket — all made out of the same merino wool, sourced from New Zealand, found in Allbirds’ popular shoes.The launch comes more than a year after Allbirds started selling socks, marking its first foray out of footwear. Earlier this year, it started selling underwear and hinted more apparel products were on the way.The new items double down on its commitment to using sustainable materials, including plants, recycled plastic bottles and now, crab shells.”Does the world really need another T-shirt?” co-founder Tim Brown asked during an interview. “The fashion industry doesn’t need another T-shirt unless it’s better.”Brown said the company first identified a waste stream, which in this case is a surplus of snow crab shells in Canada’s seafood industry. To manufacture the shirts, minerals are extracted from the shells and mixed with wool. The result: an antimicrobial fabric that can kill bacteria, Brown said.”The result is something quite special,” he said.Allbirds’ new T will retail for $48, the cardigan for $145, the jumper for $135 and the puffer for $250.While the coronavirus pandemic has weakened apparel sales, with fewer people getting dressed up for work and other special occasions, it has actually been a boon for Allbirds. Consumers are looking for comfort, and Allbirds is known for just that. The company launched its first running shoe in April. It also recently launched its own mobile app.”Our business has been extremely resilient through a really tough period,” Brown said. “On top of that, we’ve seen seen a really incredible uptick in consumer interest in sustainability.”Allbirds says it plans to expand its apparel selections. But as it did with shoes, it’s starting small.”We’re focused on a handful of essential items that we want to drill down on,” Brown said. “We sold just one shoe for the first year and a half of our existence.”The start-up, launched in 2016, is perhaps best known for its $95 wool sneaker. Allbirds sold its millionth shoe in just two years in business. It has grown to spark the interest of big-name investors like actor Leonardo DiCaprio.Last month, it landed $100 million in a Series E funding round. The funding, led by Franklin Templeton, valued Allbirds at $1.7 billion, according to a person familiar with the round. In 2018, the sustainable footwear maker raised $50 million.”I think it speaks to the broader interest in the financial and investor community toward the environment and sustainability,” Brown said about Allbirds’ latest funding round.