Alien Like Growth

I have also come to the same conclusion as some of you have, I've identified it as a species of Bryophyte, common name Liverwort. At first I thought it could have been a slime mould but did not think they came in green however it might be taking in some of the green dye in the fertilizer crossed my mind but its not that concentrated in pigment to cause that. Plus slime moulds would not be hospitable to the high levels of fertilizers given they are decomposers,. I moved onto the thought path its most likely chlorophyll and probably a spore producing plant, could be a baby fern or a moss. Landed at Liverwort after looking into other spore plants. Never knew liverworts where a thing before now. I will let it grow and see how big it will get, I find spore producing plants fascinating, they've been aorund before plants evolved to make flowers and bloom. Thanks everyone for answering!

Its just something in your substrate. All kinds of junk is in potting soil. Even pure coco i've had liberty cap mushrooms grow in it. Spores are always present in the air. Its no big deal. Just pull that shit out of there. By the way, there's another point in the corner of bottom watering. Top layer of soil is always dry, that mean fugus gnats cant live and spores and little foreign seeds can't germinate.

Just kidding (Saxifraga paniculata, with a little help of https://identify.plantnet.org/k-world-flora/identify).

plantas hepáticas - definição Como acabamos de dizer, a primeira coisa que deve ser mencionada sobre as hepáticas é que elas pertencem à classe das plantas briófitas , sendo plantas não vasculares , ou seja, sem sistema vascular responsável pelo transporte e condução de nutrientes e substâncias internamente. São também chamadas de Hepaticophytas, Marchantiophytas ou Hepaticae , embora seja usual chamá-las simplesmente de hepáticas. Recebem esse nome pela semelhança que algumas dessas pequenas plantas têm com o rim, por isso eram utilizadas na Idade Média para tratar doenças desse órgão. Aque tem aí é Marchantia Pertence à família Marchantiaceae, cuja característica mais notável é a sua cor verde intensa. Alguns exemplares desta espécie podem atingir até 30 cm. Geralmente crescem em regiões montanhosas e utilizam uma rocha para se ancorarem e assim conseguirem uma maior reserva de umidade