The official Doctor Who website allows fans with BBC accounts to “join” UNIT to receive messages and view some items in their Black Archive.

Among the items is a Homo Aqua egg which washed up on the shores of Dragonera Island in 2025. Homo Aqua eggs haven’t been seen for decades. This discovery is filed under Project Aqua, according to UNIT scientific advisor Osgood. UNIT recruits are warned to watch the seas for any disturbances.

The eggs can be seen in the trailer for the Doctor Who spin-off The War Between the Land and the Sea.

What is Homo Aqua? Osgood didn’t elaborate but this might be the Latin term for the Sea Devils. If not, there is a character in The War Between the Land and the Sea named Salt played by Gugu Mbatha-Raw. Salt’s anatomy differs from that of the Sea Devil seen in the trailer for the spin-off. Perhaps Salt is Homo Aqua.

UNIT HQ can be accessed by signing up for or logging in with a BBC account, which can be used for similar online experiences from the BBC such as BBC iPlayer in the UK.