Strange black dots

[Tilkifox]

Hi,
I have strange tiny black dots on the underneath of the leaves on my st gaya and have no clue what they are.
They're slightly raised from the leaves and are hard.
They're not bugs as there is no movement at all and I can't scratch them off.
Other than the spots, the plant is very healthy.
Kept in a conservatory at approx 21/24 degrees going down to 14/15 at night with humidity around 75.
Does anyone have any ideas?
Thanks

 

[hcarlton]

Nectar glands.

 

[Tilkifox]

Nectar glands.

Thanks so much for letting me know!
I feel better knowing its not something I've done or some sort of disease