Elon Musk’s neurotechnology startup Neuralink filed for permits to build an in-house machine shop and a biological testing laboratory for its facility in San Francisco last year.

The documentation on the company’s 2017 permits was retrieved by Gizmodo, which was able to access Neuralink’s public records. An excerpt of a letter submitted by Neuralink executive Jared Birchall on February 2017 to the city’s planning department gives some clues about the company’s plans for the facility’s proposed machine shop and animal testing lab.