Elemental familiar

Hello Sodales !
Is there a rule to bind elementals into familiars? Being neither animals or spirits they are outside the limit of normal hermetic magic or hermetic theurgy, and being from the magic realm, faerie magic can't help.

Thanks ! And please forgive any writing mistakes : english is not my native language.

This came up in my saga, but we weren't able to find explicit rules. We ended up deciding that a spirit familiar for an elemental spirit was the closest the rules had to offer.
I would like to be proven wrong though.

I've made the same ruling at some point.

I've tended to house-rule allowing things with Cunning that are not animals if they closely fit a character, such as someone with a strong connection to Terram having an Earth Elemental.

There is one thing existing in the rules that works depending on reading. Look at the Terrae Cult in TSE, on page 67. It's not explicit. It can summon elementals and limited spirits, but it doesn't specify that the familiar part gets switched at all. I would find it odd not to be. (Why could you not summon a ghost but bind a ghost, while you could summon an elemental and not bind one?)

Thanks everyone for your answers !

I think that spirit familiar and an elemental spirit are the best compromise, even if it is not exactly what I wanted.