Does a small creature hidden under your clothes also become invisible when the Invisibility spell is cast on you

Question

Does a small creature hidden under your clothes also become invisible when the Invisibility spell is cast on you?

I.e.: Our druid wildshapes into a mouse that crawls into the pocket of the jacket of my character. My character then casts the spell Invisibility at second level on myself (so one target creature becomes invisible). Will the mouse also become invisible?

The wording of the spell does seem to suggest this:

Anything the target is wearing or carrying is invisible as long as it is on the target's person

Unless 'Anything' cannot be a creature...

Ps: If this is the case, then I would also rule that if the mouse crawls into my character's pocket afterwards, it would also become invisible. At least, if you combine this with the unofficial ruling of Jeremy Crawford regarding a similar question:

Only items worn/carried when invisibility is cast are invisible, but I'd let you conceal something under them.

Answer 1

No, the Invisibility spell cast with a 2nd level slot makes invisible one creature.

The text says (emphasis mine):

A creature you touch becomes invisible until the spell ends.

[...]

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, you can target one additional creature for each slot level above 2nd.

For making invisible more than one creature, the caster must spend an higher slot.

Moreover, anything refers to items and objects, not living entities, see also this clarification.

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If a DM rules otherwise, as per the situation depicted in the question, the provided Q&A contains the discussion about items picked up while under the Invisibility spell.

Answer 2

TL;DR: The mouse is not visible but not invisible.

Firstly, as argued by @Eddymage, the mouse itself does not gain the Invisible condition:

1. The Invisibility spell, at 2nd level, only grants the Invisible condition to 1 target creature -- in this case, your character.
2. Only the items a character is wearing or carrying also become Invisible, not the creatures.

This does mean that your coat turns Invisible, however, and remains so as long as you are, even if you would remove it from your person.

On the other hand, as argued in the answer linked by @Eddymage, an object is not visible while in the pocket of the Invisible coat, or otherwise inside the Invisible coat.

While this does not provide a definite ruling on whether a creature would be subject to the same rule, any interpretation which differ here would run into weird situations: should the mouse enter the pocket, it would be visible, but any hair it sheds would be concealed and should it die... it'd disappear as well! Not only does it stretch the suspension of disbelief, it seems likely to impede gameplay and to open the door to shenanigans. I would suggest treating creatures the same as objects in this case.

Or in summary:

• The mouse itself is not Invisible.
• The mouse while in the pocket of the coat is not visible, thus Hidden.

This matters because:

1. The mouse could crawl into the pocket of the coat after you cast Invisibility on yourself, and still be Hidden.
2. Should the mouse crawl out of the pocket of the coat, it becomes visible, regardless of whether your Invisibility has worn off or not.