I noticed this sand (something like a molehill), when it was little and planned to sweep it away later, thinking it's ordinary sand maybe leaking out of the wall. To my surprise, it's growing longer and I have no idea what is behind it. There is no visible sign of ants and even if there was, why would they be transporting this sheet of mud up the wall?

Probably termite or ants. There is a hole in that wall below. Tidy the area and look closely buddy, You might find the answer.

That is Venom.

Please don't attack it otherwise it will wipe you out and eat your brain (if any).

Just pack your stuff and flee from that house as fast as you can and never look back.

It is common naa......abi you want carry am put for spirituality head?

incandescentena:
Probably termite or ants. There is a hole in that wall below. Tidy the area and look closely buddy, You might find the answer.

Hello, friend. I have dismantled it. There is no trace of ant or termite inside. The only thing I discovered is a gap wider than usual between the tiles

Assuming it's ants, what could be their endgame? Also, noob question but why would a house built with cement and concrete have this kind of muddy sand (going by the assumption that it was dug out by insects) ?

Ever8090:
It is common naa......abi you want carry am put for spirituality head?

Just noticing it for the first time tbh. Perhaps it's more prevalent in Northern villages or locations closer to a farm?