> A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age.
So tissue still qualifies. If someone says its not a fossil, that would presumably be because its not old enough (not a “past age”).
Also, I am pretty sure it wasn’t frozen when discovered since it was near the surface at a time when they were getting rain. Might have been in permafrost until they started excavating though.
What's the difference between fossilized and petrified? It can be a little confusing. A fossil is any evidence of life that has been preserved in rock. Fossils include not just organisms themselves, but also the burrows, marks, and footprints they left behind. Fossilization is the name for a number of processes that produce fossils. One of those processes is mineral replacement. This is common in sedimentary and some metamorphic rocks, where a mineral grain may be replaced by a material with a different composition, but still preserving the original shape.
What Makes It Petrified?
When a fossil organism is subjected to mineral replacement, it is said to be petrified. For example, petrified wood may be replaced with chalcedony, or shells replaced with pyrite. This means that out of all fossils, only the creature itself could be fossilized by petrification.
And not all fossil organisms are petrified. Some are preserved as carbonized films, or preserved unchanged like recent fossil shells, or fixed in amber like fossil insects.