Twitter’s future owner, billionaire Elon Musk, replied with a poop emoji. 

In a series of 13 tweets, Agrawal laid out how Twitter attempts to keep bots off of its platform including updating its rules and systems constantly and locking millions of accounts each week that can’t pass verification challenges like a captcha or text verification. The tweet thread was in response to Musk’s demands last week that he needed to verify Twitter’s claim that fewer than 5% of Twitter users were fake accounts. 

Agrawal emphasized on Monday that the company has several ways to perform spam and bot estimates internally, based on “multiple human reviews.”

“Unfortunately, we don’t believe that this specific estimation can be performed externally, given the critical need to use both public and private information (which we can’t share),” Agrawal wrote.

The CEO added that the company “shared an overview of the estimation process with Elon a week ago and look forward to continuing the conversation with him, and all of you.”

After his initial poop emoji response, Musk explained his thoughts a little more clearly.

“So how do advertisers know what they’re getting for their money? This is fundamental to the financial health of Twitter,” he wrote.

Elon Musk did not immediately responded to Fortune’s request for comment. A Twitter spokesperson declined to comment.

Musk said last week that his deal to buy Twitter was on hold because he wanted to verify Twitter’s claim that fewer than 5% of users on the platform are fake accounts.

“Twitter deal temporarily on hold pending details supporting calculation that spam/fake accounts do indeed represent less than 5% of users,” he tweeted Friday.

Although he later said in a tweet that he was “committed” to buying Twitter, attempting to hold up the deal over Twitter’s spam metrics could be a sign that Musk is souring on the $44 billion deal that he struck to buy the platform earlier this month.

Although his agreement with the company has him buying all of the company’s outstanding shares at a price of $54.20 per share, the company’s stock price is trading well below that following a widespread tech stock thrashing last week. As of Monday, Twitter was trading at about $38 per share. 

Musk’s Monday tweet is also the latest example of the billionaire using the platform to insult Twitter employees and executives. After striking a deal that prohibited him from disparaging the company or its executives in tweets, he has criticized some influential employees, including Twitter’s top lawyer Vijaya Gadde. Last month, he tweeted a meme critical of her, that included her photo. Her Twitter feed was immediately flooded with harassing messages. 

Musk has also railed against Twitter’s content moderation policies, which he said was one of the major reasons he said he wanted to buy Twitter. In the press release announcing his takeover, Musk emphasized that he wanted to emphasize “free speech on the platform.” 

“I also want to make Twitter better than ever by enhancing the product with new features, making the algorithms open source to increase trust, defeating the spam bots, and authenticating all humans,” Musk said in a statement on April 25.

Musk seems to be doubling down on his criticism of Twitter’s moderation policies. In a tweet posted over the weekend, the Tesla CEO posted instructions for how his 93.5 million followers could “fix” their Twitter feeds, which he said are being manipulated by the company’s algorithm.

“I’m not suggesting malice in the algorithm, but rather that it’s trying to guess what you might want to read and, in doing so, inadvertently manipulate/amplify your viewpoints without you realizing this is happening,” he said in the tweet.